I'm considering an upgrade from
$ uname -r 3.5.0-26-generic
to kernel 3.8.5.
Is this tested on 12.10, and is it safe to upgrade?
There's always a potential issue when upgrading the kernel, but unless your configuration is highly specialized or unique, upgrading is an option. FYI - both 3.8.5 and 3.9-rc5 are compatible with 12.04 and 12.10. Even 13.04 (beta) running 3.8.0-15 is quite stable. Good luck and have fun.
I wouldn't recommend such an upgrade on a productive system, as it can cause some big troubles with the drivers. Once I've tried such an upgrade and it really messed up with my graphic drivers. and as ubuntu 13.04 is just a few weeks away it isn't worth it. you should wait for the new ubuntu and play it save.