I'd been using my T2i mainly for controlled & well lit video (at ISO 400 or lower), and only recently used it to shoot stills at live events w/uncontrolled lighting. The higher ISO performance, as well as the autofocus was kinda disappointing.

The main points taking me back are as follows... Better ISO/noise performance, much better low-light AF, a (slightly) bigger sensor w/fewer megapixels, dual card slots (that can record simultaneously, for instant backup), and I can put my SB-800 back to on-camera duty. I also have several G lenses that had been collecting dust.
I'll still hang around here, though! The principles of photography aren't going to be changing any time soon.
