Quote Originally Posted by Jon Ruyle View Post
I'm assuming that for now, we don't know anything the relative performance of the two sensors when it comes to noise, other than a few jpg samples. That means we really don't know if one camera will have better read noise than the other, though I assume that if there is a difference, the 1DX will have the edge here. Am I wrong? (If I knew for sure that the 1DX had far lower read nose, I might seriously consider the 1DX.
True. There are now some 5DIII RAW available for download (Imaging Resource), but they're from a pre-production model, and there are none from the 1D X. Chuck Westfall has stated that the 1D X would be superior to the 5DIII in that regard, but gave no indication of the magnitude of the difference.

For me, the frame rate and build are important factors, as is what I presume will be better tracking with input from the metering sensor and the associated face tracking feature.