5d2 sample variation? Bad shadow noise.

So, I am on my 3rd 5d2. don't ask why... LoL

Something struck me while doing some quick test shots. The previous two samples had some wicked bad shadow noise even at ISO 100 with banding and all that jazz. Worse than my 60D even even at the same ISO.

The third copy is much cleaner even at ISO 1600 in the shadows.

Could sample variation be what's causing some people to claim dreadful shadows where others see no problem?

Glad I am so OCD and sent the other two back! This one is mint money, especially hooked up to my 16-35L II.

Also glad I dumped the 17-40L as it is proving to not have been as good as this 16-35 I have now. The difference in FOV at 16 vs. 17mm is very noticeable too. Heck the 16mm even gives me an extra .7 degrees over my 10-22.

Anyone else with multiple 5d2 copies notice this too?