Colin, have you seen the Rob Galbraith article on the 1D X? There are a few minor points not mentioned in the highlights reel.
14 fps is not only JPEG-only, but also with the mirror locked up. And once the iso goes above 32,000, you're down to 10 fps.
Max. sync speed is down to the 1Ds's: 1/250s. [full frame sensor => longer shutter curtain travel]
The camera can use an electronic 1st curtain to reduce vibration.
Richard: Thom Hogan is actually positing Canon and Nikon will be head-to-heading not leapfrogging, as the D4's arrival is near, and he's hearing 18MP. Everybody's racing to get a pro sports model out in time for the Olympics.