God pixel peepers are a joke. Ansel Adams surely never questioned this type of crap.
That's pretty comical, especially if you've read any of Ansel Adams' (very scientific) writing.
skitron: I'm not at all surprised by your observations. I own the 5Dc, 5DII, & 5DIII, & have taken numerous photos with friends' 5D/5DII. Banding often varies from body to body, I find. For example, it's not too offensive on my own 5DII. But it's easily seen on my 5DIII, albeit only in the vertical direction (landscape orientation).
As for comments on having two systems: Nikon for landscapes & Canon for everything else... true extended DR is extremely useful for landscapes, but often I find myself wanting to lift shadows in other types of photography where something wasn't ideal (wrong exposure b/c of backlight, flash created unwanted shadow because of suboptimal placement, or I don't have time/ability for an off-camera flash setup yet want the background landscape as well as the people in the shot). For these types of shots, the Nikon would undoubtedly be more forgiving. In fact, low read noise downstream of ISO gain application allows for more aggressive exposure compensation in post (i.e. I believe the D800 is a step in the direction of the theoretical ISO-less camera).