The dpreview review (yes that is right) on the 1Dmkiv made comparisons with the 7D as part of the review. It fairs very well, particularly if you consider you can get three! of them with grips for the same price as just one 1Dmkiv.
Dave also sent me this link comparing the 7D with the 1Dmk111 with specific considerations for bird photographers.
Now if you have been following my reviews on the 7D here, here, here and here you will have seen that I am coming to the conclusion that this is a good piece of kit for 'wildlifers' on many counts. I have still yet to do another part to my review which will cover off noise and high ISO, and how to process for best effect.
As you will have seen in this post where I got some images of Crossbills, and also yet to be posted images of Sparrowhawk in my garden, the 7D is increasingly the body of choice, with the 1Dmk111 being relegated to that of back up.
So when I see forum posts that say 'Would the 7D be a good back up to my 1Dmk whatever?'. I would say no - more likely your 1D will be a good back up to your 7D. Of course, I will caveat that specifically for bird photography at distance, which is where I have been testing it.
But the key is you need to test for your genre of photography, and not just believe others, in particular Canon's marketing spin.