Oh, just got irritated again about banding noise at low ISO. I know 5D mk2 does not have as bad banding as 7D, but anyway it would be nice with a completely random read noise, which increases the useful dynamic range.
I can't exactly say I often have problem with it on the 7D (and I've heard that the problem is less evident on 5Dmk2), but now and then it pops up, for example when pushing shadows in post-processing, and in some occasions it is slightly visible in quite bright skies too. Probably I'd have less problem if using Canon's DPP instead of third party raw development software, but I certainly don't like the idea of hiding flaws in the electronics by some inhouse secret algorithm that will not be in the third party softwares which most folks use. The less that needs to be fixed in post-processing the better.