Upload & Sell: Off
So anything that 1DX is good at?
I recommend that you try one if you can. I've been shooting with a pair of MkIV's for the past two years and picked up a 1D-X in the spring. I have since shot many 10's of thousands of frames shooting swimming, volleyball, lacrosse, soccer and field hockey.
The 1D-X AF is so fast as to be almost unbelievable. Prior to using it I did not believe it could be THAT much better than the MkIV. I normally shoot with the 400/2.8 on one body and the 70-200/2.8 on a second body. Now when I grab the second body (MkIV) it feels incredibly slow and Rebel-like. How was it that it worked so good prior to the 1D-X?
I think the biggest surprise is the viewfinder. I was prepared to hate the black AF squares. I have shot several night games and the black squares are pretty much a non-issue. Speaking of night games, I normally need to use ISO6400 on our fields and now with the 1D-X I don't even bother with noise removal (Used Neat Image with the MkIV).
The only remaining issue for me now is how quickly I can sell my remaining MkIV's and get a second 1D-X.
Oh... there is one slight negative. The battery doesn't seem to last quite a long in the X, even with the new LP-E4N battery. It still lasts for many thousands of shots, just not as long as the MkIV.