I've read a ton of threads advocating glass over body when it comes to laying out cash. But sooner or later you need to upgrade the body. What criteria do you use? My T1i is obviously not outdated, but I feel like I'm banging up against some of its limitations after a year of ownership. I shoot low light stuff quite often and find it hard to get a decent focus, so I've been considering an upgrade to a 5D MkII. But I also have an EF-S 10-22mm and a Roki 8mm FE, both of which I use extensively. Neither will work with a FF. So I was also considering a 7D for the better AF and the ability to keep using my current lenses. I don't mind shooting with a crop body. But will upgrading now just be paying big bucks for a relatively minor gain in performance? Anyone else here recently jump from a Rebel body to the prosumer level?