Also, any distribution worth its salt will accept bugs for any package it ships and (especially for something as important as the kernel) report the bugs upstream. This may be a slow process, but it does mean that bugs introduced by distributor patches are more likely to be caught.

Afaict, that site only wants bugs for the mainline kernel not for kernels modded by Ubuntu.

There is a PPA for Linus's kernel, it's great for this stuff - makes upstreamable bug reports really easy. (Also for discovering "hey, my proprietary wifi now has a free driver!")