For me at least, with my modest skill level, turning back (i.e. 180 degrees to a downwind landing) is a complete non-issue.
Below 500 ft, there is no choice but to go for what I planned, which would be something I had identified pre-takeoff. Noise abatement turns often have the happy side-effect of steering you towards suitable fields, early in the climb out.
After 500 ft, there should be better choices than a turn back, but in a typical circuit it would be a "half-turn" back anyway, as BackPacker said.
After 1000 ft, you don't need to turn back.
Edite to add:
TorqueTonight, our posts crossed. I agree with your 180+ degrees point.
Last edited by 24Carrot; 25th Jan 2013 at 15:34.