All right, I'm still out shooting, but so far my general observation is if you have the 1D Mark IV, the clear upgrade is the 1D X. If you already have a 5D Mark III, you would not substitute the 1D X for the 5D Mark III. So far I'm not seeing anything difference in regards to IQ. I did a really far crop on one photo out in a field, and the depth of detail stops shorter in the 1D X photo, likely due to the less 4 mp than the 5D Mark III. Well, now this is interesting. Like Brian mentioned, the coloring looks different because I'm thinking the 1D X and 1D4 for that matter, you can even throw in the 1Ds3, seem to be metering more accurately and the colors look a bit more accurate. Sometimes the auto ISO on the 5D3 is slightly off, even though it says the exposure is correct, whereas the 1D X, 1D4, and 1Ds3, are never wrong. Photos to come.