I know this thread has (likely) been done to death---I just wanted to share my 2cents.
I picked up a 5Dc---they've gotten very cheap now that the market's saturated with 5D2s!---and I'm loving it.
Most of my photography has been wildlife stuff, using the 7D with the 400 5.6L. But I've also enjoyed using my 35L with 7D, and have gotten some nice portraits with that combo. After experimenting with a 1Ds classic a few months back, I decided I'd like to have a full frame body to take some of the strain off the 7D and to help me get more FL mileage out of my lenses.
Holy crap is the 35L+5D an amazing combo! I know I'm losing about 5mp using the 5d instead of the 7d, but the pictures from this body are just so beautiful---I wish I could explain the difference (and I'm sure other people already have): smoother, somehow more multidimensional.... And of course, without the crop factor, the 35L goes from being a standard lens to a nice wide one, with a tremendous DoF range.
There's no way I'd get rid of the 7D---it's an awesome camera, and when I need speed and reach, that's what I'm grabbing. But to anyone considering making the same purchase, I strongly urge you to do it! 5Ds are routinely selling for $800 now, and I bet I could have nabbed mine for 750 if I'd bargained hard.