OpenSauce for Custom Edition 1.10

[Elite051]

Is OS compatible with 1.10? If not, how would I go about downgrading?

[Tnnaas]

I'm considering just sticking with 1.09 for the foreseeable future and adding patches that make it refer to the new master server.

And for the second part: uninstall, reinstall 1.00, run update 1.09 I suppose. I don't know if there's a version changer for 1.09 and 1.10, so go search.
If you do uninstall, you shouldn't have to worry about downloaded tags and maps unless you yourself delete those folders, but back them up just in case.