Have used 5.5, ran usual battery of tests, and the downhill death spiral in a science/chemistry context continues. Code wise, it is better than open weight in several ways, but you really have to work hard to fight it from creating such a heavily abstracted mess it becomes unmaintainable for humans. Requires too much handholding for me. It's scientific reasoning is more confident as well, which would be great if it were also more correct.

Open weight models are generally more humble when working at fronteir, seek human input more reliably on thi gs they have no buisness deciding on, and can be trusted to not fuck up codebase in some way. Also, the way claude talks by default and tends towards even with all the "use this standard or that" tricks, grinds my gears in a way that drive me postal.