I've got a 5d2 and a 7d where the banding is quite noticeable without even having to push shadows very much.
image I posted here:www.canonrumors.com/forum/index.php?topic=9299.0
was shot raw with my 7D; ISO 100, 1/1000, f/8, all internal processing and ALO off. Firmware 1.2.5
PP in DPP used; +0.33 EV, contrast -2, highlight -5, shadow +5 to open up some "depth" in the foreground.
if shadow is left at 0, the banding is almost not discernable.
But any value above 0 the banding begins to appear
in the dark area below the trees, this is in an area of RGB value of about 50, 35, 25, as processed, so not exactly near black and this is not much of a shadow push, frankly.
If I'd have had the lens I needed with me I could have shot this on my D5100 and the dark area would have been TOTALLY CLEAN even if I wanted to push it up to where the foreground was completely visible at lower midtones.
attached crop of banded shadow area at DPP settings describe above, (+5 shadow)
crop taken from below left of center
I've only tested 2 7D bodies, they were equally this bad. Some of you may have better ones, count yourself lucky.
The readout channel mismatch between the dual processors working on the 7D sensor's dual readout is likely responsible for the 8 pixel wide vertical stripes.
I'm reluctant to even try the v 2.0.3 firmware as it still may be buggy altho v2 firmware did improve my 5D2's banding considerably, if not enough to make me love it.