A handful of players I know have indicated that they want to participate in the Dark Sun one-shot I am working on. I ultimately decided to use Castles & Crusades as the rule system. I decided this for ease of conversion. I have told my players that I am not going for a 100% accurate mechanical conversion but instead a "thematic" conversion. It will follow a lot of the thoughts I have mentioned here - no psionics, no defiler/preserver classes, etc.
I am keeping a bunch of the races and classes that I would eliminate if it were a B/X game but, once again, not straight conversions.