Oh -- and, if you're shooting for Sports Illustrated but you're shooting golf or tennis, you'd again be a fool to go with a 1D X over a 5DIII (because of shutter sound).
True about golf, but shutter sound is barely of any importance in tennis. At least if you are shooting as a professional. As an amateur, silent shutter can be useful at times - but mainly to not annoy other spectators if you shoot very close to them. The drawback is the drop in FPS of course.
Wrong. I shoot tennis for a Division II college. The players can hear the shutter because you are THAT close in those instances. This isn't Wimbeldon. Again, don't generalize for every sports shooter. Of course I can go stand in the parking lot with a 200 f/2L lens with a 1DX, but if I am allowed to get much closer, I'm going to. The silent shutter on the 5D3 is GREAT for these matches.