Yeah, I second this, and have to call an 'ipse dixit.' None of the SS/fix riders I know run QR due to the problem of slippage (or the fact that track hubs are made with threaded axles)...Sheldon obviously has wayyyy more experience than me, but I'd never run QR on any single speed drivetrain. I think that steering a newcomer towards threaded axles is a sound move, if for nothing other than simplicity's sake.

EDIT-- I've been quickly disproved by some followup posts...