1dx will give you a much better handling with your big lenses: 85L II, 70-200, and of course future 200mm f2 IS
Keep in mind....it might take you sometime to get use to 18MP(larger pixel). Once you passed that state, I doubt you would pickup your 5D III.
Thanks Dylan - I watch out for the larger pixels. The big whites are on my shopping list too - the first one being the 300 II.
I'm tempted to order one too, but I'll wait for the Mk2. After that maybe 200/2 or 300/2.8. New kidneys grow back in few years, right, so I can keep selling them?
I considered waiting for the Mk2 as well but felt that photo opportunities can't wait. That said, if the Mk2 did come around sometime next year, I'd probably sell the 5D3 and get a Mk2.