I'm a heavy enough user that I have both the OAI and Anth $200 plans. I always use at least 50% of my weekly Opus quota at Extra setting (meaning I use double the limit of the $100 plan, at minimum). Max I rarely touch because it is twice as slow and the incremental capability gain is minimal. Usually if Opus can't sort something well at Extra, the answer isn't to use Max but to hand the issue off to GPT-5.5 at XHigh.

I too have settled into a kind of dual Claude/GPT model setup. I will often use one to review the other's work, or critique the other's plan in some way. Sometimes I'll have Claude implement a feature one way, then have GPT do it the other way, then have them both review each other's implementation. Then synthesize a final plan from the previous implementations+reviews.

I might just be having fun with models, but I have actually noticed their capabilities vary somewhat, and so my (perhaps vain) hope is that by using both, one can catch each the other's blindspots. It's still unclear to me if that's consistently happening, but I am making substantial progress in my personal and professional projects, so something seems to be working.