I called Canon support on that 1Dx - the Digic 5+ (not Digic 5) processors alone may be worth ignoring the 1D IV. The dual Digic 5+ processors (so I was told) are 6 times faster and create approximately 75 percent less noise than the DIGIC 4 processor. The rep stated this results in a lesser need for larger MB's files hence why the MB is lower then most of its similar predecessors. RAW images can be processed at 12 fps as well. That's not to mention a boat load of other cool features such as dual storage cards that can be programmed in a variety of ways (such as a real time backup or extended disk space - you choose), bracketing with 9 exposures..the list goes on. My gut instinct (being in IT) always says if you can afford it go forward with technology not backward.I dont doubt it for a second that the 1Dx will overall be better than the 1D mk4
there are however 2 things that the 1Dmk4 has you can't get anywhere else
1) 1.3 crop I want this for using my 16-35 f2.8 as a walkaround effectively 20-48mm and for getting the extra reach on using long lenses. but has better IQ than the 1.6 crops
2) AF at f8 long lenses and teleconverters coupled with item 1 it stomps the 1Dx on the long end.
Ideally i would prefer not to have the bulk of a 1 body which is why i'm holding out for info on the next 7D and just continue with the 1D3 for now