I have the (old) 1200AF ring flash and it works okay on the 7D in manual mode--which is okay for some apps, but not all. I thought it was supposed to work automatically on the 7D in P, A and S modes--but does not--unless someone can tell me otherwise.
For controlled shooting, where you have time to do some quick tests the manual exposure works just fine. I just tried it in my office on some fishing flies. Nice images.