Sorry to disagree with you, i feel Ayelike has some valid points and you are not addressing them :
1. I suppose he says why anyone will buy a new camera if it will have so similar specifications to 5D2 (the GPS adapter and PDAF alone are not sufficient in my view) when the competition has a new camera with better specs at lower price?
The *advantage* of an older body is that it is has a debugged firmware, it runs magic lantern now (!) and there's plenty of 3rd party gear around. Of course time will change that, except for the sad fact that the 5d3 doesn't take other viewfinder screens - doh.
I just had a very good look at the raw samples of dpreview with Lightroom, and I have to say up to iso6400 I cannot tell the 5d2 and 5d3 apart if I don't use the "nicer" noise signature of the 5d3 as a clue. Esp. in problematic, darker areas the 5d3 is hardly any better. The d800 sensor blows Canon out of the water here - so that can't be it.
But there are some harder and softer facts that make the 5d3 an upgrade, but everyone has to evaluate him/herself if it's "worth it".I'm very torn myself because $3500 is very ambitious indeed for the 5d3, it is an enthusiast model after all with just 150k shutter rating, and Canon cut some corners like the crippled sd card controller & no assist beam.
* 6 fps (vs 4 fps mk2 or d800) - this really is a difference for bracketing or quck burst shots
* more precise af servo system - though it sucks in one-shot mode for lenses slower than f4, and it seems to have speed issues because the original design seems to have the faster 1dx in mind.
* quiet shutter mode - could make a difference if you are allowed to shoot in some places or not unless mirrorless cameras are around
* better control layout (the 5d2 is like a 40d on speed, the 5d3 is more like 60d/7d)
* better auto white balance
* no moiree in video
* better lcd like 1dx
* better sealing for peace of mind, though certainly not a 1d outdoor body
* updated firmware hardware support (radio flashes, gps)
* expanded firmware features like bracketing, though magic lantern on the 5d2 (focus peaking, unlimited automatic bracketing, timer shots ...) is still way ahead.