Well I have opus 4.8 pinned :) More "frontier" models seem to create more busywork for themselves in my limited testing.

if I can put my tinfoil hat on for a moment, creating more tokens / busywork is in their investors' / IPO interest

I pinned 4.8 because 5 started to build the application on its own (native windows, visual studio NOT code). I wouldn't mind much except it seems to take much longer than me alt tabbing and hitting control+b.

Also it seems to start subagents for random stuff, it didn't before with my development style. And then the main thread gives you a partial answer and tells you it's waiting for the subagent to finish :) What's the point?