I noticed a bit of banding from the D7100, but it wasn't too bad. It seemed to affect the second D7100 more than the first.If there is going to be a d400, I hope Nikon go back to putting a Sony Exmoor sensor in it, The toshiba one in the d7100 does not impress me at all. If you need to lift shadows, they have really bad banding whereas the sony Exmoor sensors are ultra clean and by far and away the best sensors in the market. Canon have nothing that comes close to the Sony sensors.
I am also not 100% certain that the AF issue I experienced wasn't a Sigma-Nikon AF communication issue between the lens and the bodies. In switching things up, I went to a D600 and am slowly switching to all-Nikon lenses. I have noted that AF-Auto works better on the D600 with Nikon 24-85mm lens than it ever did with the D7100 and Sigma 17-50mm I had. Not really sure why for sure, but it just does.