I bought the EF-S 17-55mm f/2.8 in November. Zero regrets. It's the best all around lens I've ever used. One of these years I plan to move up to ff and I won't be able to take this lens with me. But I doubt at that time I will get rid of my crop-sensor bodies, so this lens will still have a place in my camera bag. I determined to get the best glass for the body that I own now (which is the EF-S 17-55) and cross the FF bridge when (or if) I get there.