So happy to have diversified my model providers this past couple of weeks. GPT-5.5 has had no trouble slotting into Opus workloads. Will be fun to try out more of the models as time goes on to build some resiliency into my engineering workflows :).
I found GPT 5.4 terrible. I just tested 5.5 and compared with opus its still not great.
*But* I don't work with the defaults -- I work with my own prompt framework based off of superpowers.
Given sufficient prompt scaffolding, I've found the models relatively interchangeable -- _I might_ be getting some of this for free by basing my own system off of superpowers which is used across various harnesses -- In other words achieving this kind of portability may be a lot harder than it looks and I'm benefiting from other people's work.