I was at West photo in Minneapolis yesterday. Baught a C stand and he let me fiddle with a 1Dx yesterday. Purposely shot into into some shadows and I underexposed by 2/3 at 12800 ISO
DO NOT TOUCH A 1DX
you will want one and they cost $7000.00
But -2/3 at 12800 ISO was cleaner than my 5D3 at 6400 ISO---unfricken believable. The camera feels like an MKIV in your hands, ergos are awesome, menu lay out is nice, speed is insane, and the AF system looks very impressive and looks like a bit or reading on how to set it up. There is stuff on it thats not on the 5D3 that i noticed as I thumbed through the set ups and options........Looks to be crazy good. I also talked to the guy that returned it from the weekend rental......his response was best camera he has ever used and said he was probably done with One shot after using servo on it.....zero misses for his project.
probably worth an upgrade from a 5D3 if you have the $$$ to spare