I'm 75% through my Fable usage on the 20x plan. Here are my impressions: 1. Fable has made incisive product-level judgments I haven't seen from any other model. A good comparison here is the quality of advice my PhD advisor, who won a Nobel in economics, would give on any big picture career or life advice, or any advice on anything in economic history. Fable cannot give Joel's quality of advice on areas in which Joel is an expert, but Fable can give Joel-tier (IMO) advice on areas on which it's an expert through its innate ability PLUS you giving it the right context. 2. I also applied Fable to a wiki-style repo I've created for career planning/strategizing. Some of the advice Fable gave was off base, but this was because of incomplete context in the wiki which I had to remedy rather than Fable's own errors. Fable's advice was quite good after remedying those errors. 3. I used @shadcn 's "improve" skill (github.com/shadcn/improve) on several repos. For me the results were not mindblowing, and it missed some improvements I later found through conversation with Fable. But I still think the skill is a good use of tokens. 4. GPT-Pro *is* comparable to Fable IMO, but since it's harder to use interactively, you can only really use it to get "static" feedback on some code or doc. I had Fable use GPT Pro with Oracle a few times and Fable commented positively on GPT Pro's feedback. 5. I didn't experience a single instance of Fable getting routed to Opus 4.8 by the security classifier. Here's the set of projects to which I used Fable: - A software to automate decision making in causal inference (difference-in-differences, regression discontinuity, etc) - A software to automate my video editing - An economics literature review automation software - Cleanup of my skills repo & optimization of my skills - The aforementioned career planning repo Overall I like Fable, and I'd be very happy if Anthropic consistently gave you 50% of your usage a week with Fable, like they have in this post-export controls trial period. I wouldn't call Fable mind-blowing, but it is better than GPT-5.5, and I'd keep using it consistently if Fable was available on my subscription. The key to optimizing Fable usage is delegating implementation to Opus or Codex.

Now that there's a $100 ChatGPT Pro tier, it's a no brainer for any economist to choose ChatGPT over Claude at EVERY price point. 1. $100/mo now gets you access to Pro in the web UI, which is invaluable for academic work. See xitter.cf/aniketapanjwani/status… for how to optimally use Pro. No Anthropic model compares 2. $20/mo usage with Claude Code is a joke. $20/mo usage with Codex is limiting but not that far off of $100/mo Claude Code usage. I've myself experienced getting capped within an hour at $100/mo with Claude Code with normal usage. With $100/mo with Codex, for the typical economist's usage, you'll never hit 5 hour or weekly limits. 3. GPT 5.4 itself is a much better model than Opus 4.6 for almost everything economists would care about. CC has a better developed plugin ecosystem, subagents in CC work better IMO, and CC IMO is by default a better writer. For anything else - helping you understand papers, write code, plan out structural estimation, think through identification arguments, choose between estimators - I'd prefer Codex. 4. Whenever OpenAI has an outage, they reset usage for everyone, and they keep extending the length to which you get double usage from your subscription (now until end of May!). Anthropic is crunched heavily for compute and seems to be both explicitly ( xitter.cf/trq212/status/20372546…) and perhaps surreptitiously (xitter.cf/om_patel5/status/20417…) trying to restrict their compute provision. 5. The Codex Desktop app is hands down the best interface for agentic coding right now. The Claude desktop app is probably the worst way to use Claude Code (go to /r/claudecode to read about all the bugs people encounter). There's a dearth of educational material about the Codex Desktop App though (which I will be solving soon) I walk through each of these points in more detail in this YouTube video: youtu.be/_oKPa8_7w3Y?si=1Bru… So, what are the switching costs from Claude Code to Codex? > The models feel different/act differently. You have to get used to it. > Skills are an open format, so you can just copy all your skills over to ~/.agents/skills from ~/.claude/skills . There are some CC specific skill features which don't port over 1 to 1 to Codex. > Subagents are configured differently and act differently in CC compared to Codex. > Hooks are experimental in Codex and you have fewer options of harness actions onto which you can configure hooks. I'd say if you haven't yet started with these tools, choose Codex for sure. If you're hitting your Claude Code session limits regularly, then also switch to Codex for sure. If you're not hitting your session limits, or you have a $200+ budget, I'd recommend getting a $20/mo Codex sub and just try it out/feel it out. Codex and CC pair well together anyway, for example by having one write a plan/code and having the other review the plan/code. I have Codex at a $200/mo subscription and CC at a $100/mo subscription - that works well for me, I use Codex 80% of the time and CC 20% of the time.