Upload & Sell: Off
As far as it goes with the 1DX vs D4, these guys seem to think the 1DX is superior. Superior enough to dump an entire Nikon system including a new D4 to switch to Canon.
My friend has a D800 which I got to play with for a day. No scientific tests here... but VS my 5D2, the D800 felt quicker in the AF department. Against my 7D there was no comparison... the 7D smokes it. I played with all-points, one-point, one-shot, and continuous. All anecdotal, but backed by 30 years of experience. If I were a landscape, still-life, product, etc., shooter, I'd no doubt prefer a D800. For anything that moves, Canon is it. Count the number of white lenses at the Olympics VS black.