I'll try post some stuff later in the week. Nothing to scream about but it's the DR and ISO3200+ noise difference that's most noticeable, compared to the 5D2. I'll probably use it for topside and keep the 5D2 for uw until the housings start coming out. Not going to get much money for the 5D2 housing/camera combo anyways.
All-I in 90mb/s(!) is a bit higher in resolution but not very significantly so, but better moiré and aliasing control.
I don't think there's much of a difference between the 1Dx/5D3/D4/D3s in terms of noise now... probably in the 1/3 stop range. The 61 pt AF system tracks better and acquires subjects with a bit more spirit. But for normal shooting, it's not much difference. Haven't tried low light scenes yet, maybe that's where the difference will lie.
It's an upgrade and an incremental one (albeit very impressive). That's what Canon usually does anyhow. It's not a game-changer for DSLR like the 5D2 was, since 1080p video is everywhere and the incremental improvements aren't as impressive as Nikon's huge jump from near zero to hero.
** Dammit, dead pixel! Have to send it back!