I have to go with the half moon camp, also, but that's due to tradition. One day, when I have the option, I'm going to retrain myself on a foot switch attached to the expression pedal. It makes much more sense because there are many times when I like to switch and I have to take my left hand off whatever I'm playing to do it.
Or, to combine the best of both worlds, I'd position the half moon closer to the middle of the keyboard so I can flick it with my wrist or thumb.