I have had no stability issues with CM7 nightly from March 20. CM9 variations still have enough issues that I wouldnt recommend it unless your the type that likes to have the bleeding edge and are willing to pay for it. Browser cant be rotated without crashing, a few camera issues, etc. As others have posted, it's usable, but it has issues.
Neutrino is a very nicely tweaked option if your a minimalist. Not for me personally as it's a bit to bared to the bone (I end up installing a ton of stuff and end up near stock size after it's all done), but I did use a lot of the tweaking.