EOS 5D Mark III vs. EOS 1D X - Differences?

[neuroanatomist]

As I go through the decision process, the first step is a thorough evaluation of the differences between the two bodies. Here's what I've come up with so far:

Worth noting is that the AF sensor is the same for both bodies, meaning the same number and type of AF points, and importantly, the same -2 EV sensitivity. As previously mentioned, the metering is different, and the data fed to the AF by the 1D X metering sensor should result in superior AF tracking, including face tracking, not possible with the 5DIII.

Some noteable features shared by both are the two AFMA settings for zoom lenses (and serial number awareness), the ability to set a minimum shutter speed when using Auto ISO, and the multi-exposure capability.

For those using an Eg-S screen for manual focus with a 5DII, the fixed focus screen of the 5DIII is a disappointment - there will likely be third party screens available down the line, as there are for the 7D, but changing them out is not for the faint of heart, and is best done by sending the camera in to the screen vendor.

Still not certain which way I'll go in the end. The 1D X comes out to $2800 more expensive (adding $500 for the BG-11 grip to the 5DIII cost) - enough to cover a 24-70mm f/2.8L II and the new 600EX flash (which I'd be getting for the 1D X anyway). But aside from the savings in getting the 5DIII, I do have the budget to cover the 1D X, so that's not really a limiting factor.

Thoughts and advice from the forum?