I'm coming to this discussion late, but thought I'd offer my experience. I bought a 7D early in 2011 to supplement my 5D classic.
There is no doubt that the 7D is a much faster handling camera than the 5D or I believe the 5D II. That's why I bought it. I always shoot RAW and use various programs for post processing. I typically shoot at ISO 100 or 200.
I had quite a bit of trouble getting images that I liked from the 7D at first. The images are definitely different than what my 5D classic produces. There is more detail, due to the additional megapixels, but there is also more noise. I had to get used to using more noise reduction for my RAW files and less sharpening. (Of course sharpening depends on the lens and other factors too.)
I decided to keep the 7D as a sports/action type camera, since the 5D is certainly not good for those subjects. I got the 7D as a refurb through the Canon Loyalty program so it was not terribly expensive.
Working with the 7D has made me really appreciate the image quality of the 5D. It's hard to describe exactly what it is that I like, but I will note that I can manipulate the tone curves a lot before the image starts to break down - much more so than with the 7D
Hi Mike; This is great information since mostly people compare the 7d to the 5d2, and not to the 5dc.. Since I own a 5dc, and was considering a 7d, I wanted someone's experience with these 2 Cameras and always wanted to ask someone if I would see an improvement in IQ if i got the 7d after I already use the 5D. I mostly do scenery/street/people. Not so into sports/action yet, but the extra reach of the 7d (APS-C +higher pixel density) always made me think about it ... any thoughts from you on the 7d/5d noise & IQ would be helpful !!