My personal opinion is that the best kernel for any given ROM is the one the developers include with their ROMs (otherwise they wouldn't include it). YMMV.
And yes, I do miss FroYo's stability every time something "weird" happens with one of the GB ROMs I play with. Each succeeding GB ROM gets better, so there's hope. In the meantime, when I absolutely/positively MUST count on my phone to work, I boot back to my original, stock (rooted) FRG83G image.
Check out Sourcery 2.2. Seems to have the customization features of CM, but with FroYo's stability. Even better, it's based on the LATEST FroYo (2.2.2)... most custom FroYo ROMs are based on 2.2.1, which has a serious SMS bug.