I've got a 5D, 7D and just purchased the 5DMKII. I too prefered the 5D over the 7D and would usually take along both when I went off to shoot whatever I wanted to shoot.
Still, at times I regreted getting the 7D because I was so close to getting the 5DMKII last year but was swept up with all the talk of the 7D. Not disappointed in the least with the 7D but there's just something about the 5D ... maybe a lot of things ... that keeps it a step up over the 7D. And I have no plans on getting rid of the 7D ... it's a great camera.
So I got the 5DMKII a few weeks back and to be honest ... from the little I've been able to use it, it blows me away. I do not shoot a lot of action photos even though I do spend time shooting my 8 Labs doing whatever it is they happen to be doing, but from what I've found, the AF is fast and accurate and I have no problem getting "action" shots ... not 8 per second like the 7D but that's an entire different opinion as far as I'm concerned.
Shot a few hundred photos (and a number of videos) at a dog show yesterday. The lighting in there was AWFUL! Never been to a dog show with such terrible lighting. Cranked up the 5DMKII to 6400 and all in all, got some pretty good shots.
For me, I'd choose the 5DMKII over the 7D without hesitation ... FF, IQ, "real" WA! ... though I see the two as a great combination, possibly swaping the 7D with a 5Dc depending on what I'm shooting.
These aren't award winners by any means but here are a couple random shots I just picked. Shot a dog show last december with better lighting using the 7D and was just as happy with what I got. First one is cropped & resized, 2nd one is just resized.
I started with my 24-70 f/2.8 then switched to the 70-200 f/2.8 L IS and was able to get all the shots I needed, ringside. Couldn't do that with the 7D / 70-200 combo last December.