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TL;DR

In a Sept. 29, 2026, workflow update, Thorsten Meyer says he will use Claude Opus 5.5 for building and newly released GPT-6.1 Sol for research and code review. His comparison, based on Artificial Analysis Intelligence Index v4.3.x, finds large differences in reported task costs, but the results do not establish which model will perform best on other users’ work.

Thorsten Meyer said on Sept. 29 that he will use Claude Opus 5.5 as his main model for building and the newly released GPT-6.1 Sol for research and review. His workflow update argues that reported cost per task can be as relevant as model scores, while stressing that the benchmark comparison does not settle which system suits an individual workload.

Meyer bases his comparison on the Artificial Analysis Intelligence Index v4.3.x, which he describes as a measure of general capability rather than a verdict on a particular user’s work. In the figures he cites, Opus 5.5 scores 58 at its highest setting and costs $5.98 per task. GPT-6.1 Sol scores 51 at xhigh and costs $0.39 per task. Those figures make Sol a less costly option in this comparison, but the index scores alone do not show how either model will perform on a specific project.

Meyer assigns Opus 5.5 to features, APIs, multi-file work and refactors, using its high setting for regular development and xhigh for difficult work such as architecture or migrations. He assigns Sol to detailed investigation of a file or code change, plus a separate review of Opus’s output. He gives Sol’s high and xhigh costs as $0.32 to $0.39 per task, describing that price as low enough for routine review.

The comparison also covers Claude Sonnet 5.5, Claude Fable 5.1, GPT-6 Astra and GPT-6 Luna. Meyer lists them as alternatives for narrower jobs, rather than defaults. He says Sonnet’s high setting is its best value for his uses, while Luna is suited to bulk classification and extraction. These are Meyer’s workflow choices, based on the figures and tasks he describes; the source does not provide independent tests of those assignments.

At a glance
reportWhen: Published Sept. 29, 2026; GPT-6.1 Sol w…
The developmentThorsten Meyer published an AI workflow update on the day GPT-6.1 Sol was released, assigning it research and review tasks alongside Claude Opus 5.5.

Opus builds. Sol reviews. Jev decides.

The September 2026 AI stack in one page: six frontier models on one price curve, and a decision model for the high-volume judgements that do not need a sentence.
Scores: Artificial Analysis Intelligence Index v4.3.x. Data as of 29 September 2026.
BuildsClaude Opus 5.5 at high or xhigh effort
Digs and reviewsGPT-6.1 Sol at high or xhigh effort
DecidesJev on high-volume yes/no and routing calls

One price tape, six models

Put every model on the same cost-per-task ruler and capability looks compressed. The bill does not.
Price tape: cost per task of six models on a log scale, from GPT-6 Luna at $0.07 to Fable 5.1 at $7.63$0.05$0.10$0.50$1$5$10cost per task, log scale: each tick is a different order of magnitudeGPT-6 Lunaindex 37 · $0.07GPT-6.1 Solindex 51 · $0.39 (xhigh)GPT-6 Astraindex 53 · $3.26Opus 5.5index 58 · $5.98Sonnet 5.5 · index 56 · $7.60Fable 5.1 · index 53 · $7.63about 100× from the cheapest to the priciest, but only 21 index points between them

Score against cost, at every effort setting

Each dot is an effort level. Opus 5.5 at high already matches Astra and Fable at max on this index, for less money.
Intelligence Index score against cost per task for each effort setting of six models$0.01$0.10$1$102030405060cost per Intelligence Index task, log scaleindexOpus high / xhigh: my defaultOpus 5.5Sonnet 5.5Fable 5.1GPT-6 AstraGPT-6.1 Sol (new)GPT-6 Sol (Sep 22), dashedGPT-6 Lunaup and to the left is better
Astra and Fable are shown at their top published setting. Luna starts at $0.0045 per task. GPT-6.1 Sol has no low or max setting published yet.

The effort dial moves the bill more than the model

Going from medium to max on Opus costs 4.46× more for 7 points. That is why I run high or xhigh.

Claude Opus 5.5

$0.55
42
$1.34
51
$1.82
54
$3.46
56
$5.98
58
low
medium
high
xhigh
max
Solid bars are where I run it. Max adds 2 points over xhigh for 73% more cost.

Claude Sonnet 5.5

$0.41
36
$0.59
41
$1.08
47
$2.74
52
$7.60
56
low
medium
high
xhigh
max
Best value is high. At max it writes about 193k output tokens per task, the most measured.

GPT-6.1 Sol: near-Astra scores at a fraction of the price

Launched 29 September at $2 in and $10 out per 1M tokens. It sits 1 to 2 points under Astra and Fable, and Opus xhigh still leads it by 5.

Three published settings

SettingIndexCost per taskOutput tokensFirst token
medium48$0.2115M5.3 s
high50$0.3225M57 s
xhigh51$0.3936M69 s
Median for comparable models is 82M output tokens. High and xhigh are not interactive: plan for a wait before the first token.

Same score band, very different bill

GPT-6.1 Sol xhigh
$0.39index 51
Opus 5.5 high
$1.82index 54
GPT-6 Astra max
$3.26index 53
Opus 5.5 xhigh
$3.46index 56
Fable 5.1 max
$7.63index 53
Cost per Intelligence Index task. A one-point gap is inside the noise.

My stack: who builds, who reviews

Opus does the work. A second model family reviews it, because a different reviewer catches what the author cannot see.
Stack diagram: Opus 5.5 builds at high effort, escalates to xhigh, and sends every change to GPT-6.1 Sol for review; Astra or Fable give a second opinionOpus 5.5 · xhighhard problems: architecture,migrations, trust boundariesOpus 5.5 · highMAIN BUILDERfeatures, APIs, multi-filework, refactorsescalate when it gets hardGPT-6.1 Solhigh or xhighdigs into details andreviews every change$0.32–0.39 per taskdifffindingsAstra or Fablesecond opinion, 8 to 20×the cost per taskif they disagreeSonnet 5.5 · Lunaside work: scopedsubtasks, bulk checksand routingFailed review? Hand Opus the failing case and the evidence.Never just “try harder”: effort cannot supply a missing requirement.
Effort is not capability. Turning the dial up does not make a model smarter.
Effort cannot fill gaps. A missing requirement stays missing at any setting.
Different model, same spec. That is not independent review if both read the same flawed brief.
Green tests are not approval. Passing tests only prove what the tests cover.

Cheaper tokens are not cheaper work

Illustrative, not measured: $1 of model time plus 4 minutes of review at $45 an hour. Halving the model price saves 12.5% of the total. One extra minute of review erases it.
$4.00
review $3.00
model $1.00
Baseline
$3.50
review $3.00
model $0.50
Model price cut 50%
$4.25
review $3.75
model $0.50
Cheaper model plus 1 extra minute of review
Track cost per accepted result: model, tools, review and rework, divided by the results someone actually uses.

Read the numbers with four warnings

The index movesFable scored 66 on an earlier version and 53 on v4.3. Compare within one version only.
Fallback is includedFlagged cyber and biology tasks route to older Anthropic models, now on Sonnet 5.5 too.
Max is not productionReal deployments run medium or high, where gaps narrow and costs fall.
Your work decidesShadow-test on your own tasks. Budget cost per task, not per token.

Part 2: Jev, the model that decides instead of writing

Jev cannot write, summarise or extract. It answers narrow typed questions with a probability and an honest confidence, in under a second, for about $0.04 per million input tokens.

One call in, typed answers out

Your code, not Jev, decides what to do with each answer, usually by confidence band.
Jev flow: state and typed questions go into one Jev call; typed answers with confidence come out; code acts alone, escalates the gray zone, or logsStatea ticket, a story,a site profile,a log line …+ typed questions,many per callJevone call0.3 to 0.9 s$0.042 / M tokens inAnswersnoul: 0.03choice: billing p 0.91, conf 0.86score: 2.7 of 3 conf 0.64code branches on thisAct aloneconf ≥ 0.8Escalategray zone toLLM or humanLogmeasure first

Three question types

noul
A yes/no question. Returns the probability of yes, 0 to 1.
gates, flags, filters
choice
Pick one option. Returns the choice, a probability per option, and a confidence.
routing, classification, taxonomy
score
Rate on your ordered levels. Returns a position (it can fall between levels) plus a confidence.
quality, fit, severity, priority

Confidence is the superpower

In my own measurement on a 31-topic classification, Jev agreed with a frontier LLM almost every time it was sure, and rarely when it was not. So: decide the clear cases, route the gray zone.
confidence 0.8 or higher
97–99%
all answers
89%
confidence below 0.5
42%
Agreement with a frontier LLM, my production data, September 2026, rounded.

Three uses running in my publishing operation

About 90,000 decisions so far. Checks I could only afford on a sample now cover everything.
$2.01
Language check
78,889 articles scanned overnight. 1,576 in the wrong language found, 1,553 fixed in place.
22%
Relevance gate
About 10,000 story-to-site pairings judged in 3 days. Only 22% were clearly on-topic.
89%
Classifier fallback
Agreement with the primary LLM across 31 topics, used when that LLM errors.

The fit test, then the shadow test

Use Jev only when all four hold. Then prove it on past decisions before it acts on anything.
High volumeThousands of small calls, not a handful of big ones.
Narrow questionNo multi-step reasoning needed.
Cheap errorsOr unsure cases go to something smarter.
Heuristic failsVisibly, and measured, not assumed.
  1. Replay 300 to 500 past decisions
  2. Compare overall and per confidence band
  3. Read 20 disagreements, decide who was right
  4. High band at 95% or better?
  5. Own flag, off by default
  6. Canary on 5 to 10 units
  7. Roll out in the confident band only

24 use cases, sorted by how well they fit

Start from the strong fits. The amber ones need a measurement before you trust them, and the red ones fail one of the four conditions.
in productionstrong fitmeasure firstpoor fit

Proven in production

  • 1Relevance gate
  • 2Language check
  • 3Classifier fallback

Publishing and content

  • 4Thin-source detector
  • 5Same-event dedupe
  • 6Product fits roundup
  • 7Disclosure present
  • 8Headline quality
  • 9Comment moderation

Commerce and support

  • 10Support-ticket routing
  • 11Return-reason coding
  • 12Review to feature complaints
  • 13Catalogue taxonomy
  • 14Order-fraud pre-triage

Software and AI systems

  • 15LLM guardrail
  • 16RAG passage filter
  • 17Citation check
  • 18Tool and intent routing
  • 19Log-line triage
  • 20PR risk triage

Business ops and home

  • 21Inbox triage
  • 22Expense categorisation
  • 23Lead qualification
  • 24Smart-home intent

Limits, cost and one hard rule

No writing, summarising or extractionPair it with an LLM for the write step.
No world knowledgePut a snippet in the state; a bare name means nothing.
Reads your wording literallyA rewording moved my results about 2 points. Freeze it, re-measure after changes.
Weaker on non-English, maths, datesKeep those checks on an LLM. Early access, hosted API only.
100,000 decisions ≈ $2.50
About 60M input tokens at $0.042 per million, output free, roughly 600 tokens per three-question call. Latency 0.3 to 0.9 seconds.
Never the sole decision-maker for consequences about people. Hiring, credit, medical and legal outcomes stay with a human. Jev can sort and flag. A person decides.
Sources. Model scores, cost per task and speeds: Artificial Analysis, Intelligence Index v4.3.x, including the GPT-6.1 Sol medium, high and xhigh pages, checked 29 September 2026. Astra and Fable scores from the Artificial Analysis v4.3 announcement. Jev figures are my own production measurements, September 2026, rounded. The review-bill example is illustrative. Read the full article on thorstenmeyerai.com.

Why Cost Shapes His Review

Meyer’s main practical point is that a lower model bill can make a second review more affordable, but it does not automatically make the full task cheaper. He says a small token-price saving can be erased by an extra minute of human review. His example is expressly illustrative, not measured, so it should not be read as a general estimate of labor costs.

His approach also makes review a distinct step: one model produces the work, and a model from another family checks it. Meyer says that arrangement is more useful than asking Opus to review its own output. He also cautions that a different model cannot compensate for a flawed specification, and that passing tests alone is not approval to ship. The practical implication is that model selection, review and human judgment all remain part of the workflow.

How the Model Rankings Compare

Meyer frames the market as a price curve: in the index snapshot he cites, six models are within about 20 points, while their listed task costs differ by roughly 100 times. Opus 5.5 leads his table at 58 points; GPT-6.1 Sol is listed at 51 at xhigh, while Luna scores 37 and costs $0.07 per task. The range reflects the particular index and task-cost figures he reports, not a universal price for every user’s prompt.

Effort settings change the comparison. Meyer reports that Opus rises from 51 points and $1.34 per task at medium to 58 points and $5.98 at max. For Sonnet 5.5, he lists max at 56 points and $7.60 per task, compared with 52 points and $2.74 at xhigh. He also reports that max-setting Sonnet generated about 193,000 output tokens per task on the index. These figures explain why his own default is below max, though they do not prove that the same setting is best for other tasks.

GPT-6.1 Sol launched on Sept. 29, Meyer writes, at the same listed token prices as its predecessor: $2 per million input tokens and $10 per million output tokens. Artificial Analysis had published medium, high and xhigh results in the snapshot he used. Meyer notes that the higher settings took 57 to 69 seconds to first token, a delay that may matter for interactive work. He also says the index had not yet published low or max results for Sol.

“The practical reading: Sol is not the model I ask to build. It is the model I can afford to run on everything.”

— Thorsten Meyer, in the Sept. 29 workflow update

What the Benchmark Cannot Show

The source provides one author’s workflow and a snapshot of third-party index results. It does not report a controlled comparison on Meyer’s own coding tasks, disclose the full task mix behind each cost figure, or establish that the cited results predict performance for other users. Meyer says one index point is inside the noise, and recommends shadow-testing before making a switch.

It is also unclear from the source how the listed task costs translate to a reader’s own usage, including prompt length, output length and selected settings. The source’s final discussion of the cost of human review is incomplete, ending mid-sentence. Its available text therefore does not provide a complete calculation of total task costs.

Test the Workflow on Real Tasks

Meyer recommends shadow-testing models against the work they would handle before changing a workflow. That would let teams compare output quality, latency and cost on their own tasks against their existing process. The source does not give a date for additional benchmark results or report a broader deployment beyond Meyer’s stated choices.

For GPT-6.1 Sol, a next point to watch is whether Artificial Analysis adds the low and max settings that Meyer says were not yet available in the Sept. 29 snapshot. Until then, his recommendation is specific: use Opus for building, Sol for detailed review and research, and test alternatives where the task warrants it.

Key Questions

What changed in Meyer’s workflow?

He says Opus 5.5 remains his main model for building, while newly released GPT-6.1 Sol will handle detailed research and review.

Why does Meyer use GPT-6.1 Sol for reviews?

He cites a task cost of $0.32 to $0.39 at high or xhigh and says that price makes routine review affordable in his workflow. The figures come from the index snapshot he cites.

Does the index show which model is best for every task?

No. Meyer describes the Artificial Analysis Intelligence Index as a measure of general capability, not a verdict on a specific workload, and recommends shadow-testing before switching.

What trade-off does Meyer report for Sol at high settings?

He lists first-token times of 57 seconds at high and 69 seconds at xhigh. That delay could make those settings less suitable for interactive work.

Source: ThorstenMeyerAI.com

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