Skiing telephoto for crop body
I'm starting to look into picking up a telephoto lens to use on my 20D. I'm just starting out so it doesn't need to be anything overly fancy/expensive, but I want something somewhat decent. I also have a Sigma 17-70 OS HSM and Canon 50 f1.8. I recently inherited a Canon 75-300 II non-USM from my grandfather, but I'm finding the lens a bit slow for anything less than pretty good light, and the AF hunts a lot.
I like the range of the Canon 55-250 and am wondering if there exists anything with a similar range that's a bit of a step up. Anything higher end seems to start at 70, and I feel that having 55 at the wide end would add versatility.