In case anyone cares to see what the 1DX looks like against the top DXO camera for dynamic range (D800E) and against the top DXO camera for high ISO, here is a set of comparison images.
This is a little test that I did a month or two ago with a couple friend's cameras and my 1DX. Canon 1DX (Canon's best) vs the D800E (best DR, best overall) vs the D3S (best high ISO). First up are full frame images then a 100% crop comparison. All tripod mounted, live view focused, identical exposure settings, shot in RAW, processed in LR 4.2, all sharpening and luminance NR set to zero. Color NR set at 30.
First pairing is 1D X and D3S at ISO 25,600. Second pairing is the 1D X and D800E shot with underexposed foreground then with +3 exposure added in LR.
1DX ISO 25k full frame
D3S ISO 25k full frame
1DX ISO 100, 3 stop push full frame
D800E ISO 100, 3 stop push full frame
100 Percent Crops of above
I think for me the takeaway is that the image quality performance of all these cameras has crossed the point where they can all capture excellent images and the differences in the high end DXO sensor scores are less important. Given that, my preference leans towards the camera that is most capable for getting the shot in the heat of the moment, and the 1D X is darn good at that. If you need to get the shot, at the decisive moment, in focus, with accurate WB/color/exposure, the 1DX is pretty much the best game in town.