Voluntarily downgrading to Sonnet 4.5 level performance sure is one way of avoiding imagined degradation in Opus 5.5...
Personally I was forced to use only GPT-5.6 Sol at work instead of Opus 5.5, and it was so much worse.
Benchmarks that control for benchmaxxing indicate all open-weight models behind 5.6 Sol and roughly at the level of GPT-5.5.
And that's for the latest large ones, much less local Qwen 3.8 Flash Next.
I would regret such a downgrade.