Then the nerf, and the massive uplift in tokens for 4.7, a model which I find lazy and prone to hallucinate.
It's probably time to try GPT5.5. Like many I'm pretty heavily invested in the anthropic ecosystem at this point, which I suppose gives another strong reason to make the switch.
ChatGPT 5.5 seems capable, although a bit stingy with “thinking” compared to earlier models, and I never run into session limits.
Even operations and GTM are all at "professional" level (which I think is vaguely equivalent to 5x).
On the other hand, this year I’ve been in the habit of using codex as a bug finder / audit layer, where it shines, and I can tell you, Opus makes a lot of mistakes, and as we all know struggles with laziness — and has gotten good at encoding that laziness into the codebase (// Per instructions, pass this test by default) where it can live for a long time. So, Opus had spoiled me, but more with its ability to sketch holistically than its ability to put out perfect codebases.
Upshot - it was good to switch horses for a while, as you mention. Slightly different skill sets there. And I still reach for claude especially for initial design. But right now the daily driver is 5.5 / xhigh fast mode, and it’s very capable.