I make a point of never going beyond about 220k, unless absolutely necessary (and it's almost never necessary), anyway, even with models that degrade more slowly, so this is just a discount.
Heck, agents don't start editing before they're already at 70k for me.
I've played with explorer agents giving exploration summaries to help the implementer agents use more of their context for implementation, but it doesn't work as well. There's always something lost in the handoff.
My understanding is that models can suffer “context limit anxiety” and a higher context limit will make it perform better especially as the context expands