I've dropped my bike twice. One of them was attempting a u-turn on an uphill. I thought I had enough forward momentum to complete the turn by just coasting, but the hill was steeper than I thought and I ran out of forward movement and couldn't get on the gas fast enough.
After that, I found an empty parking lot that had a pretty good slope to it and practiced u-turns using friction braking. I do all of my tight turns using friction braking now, even on flat ground. I'm still not great at tight maneuvers, but I can comfortably make u-turns in less than 25 feet... 20 feet if I'm careful, but they're very slow.
I don't know what the turning radius is, but I don't want to try and make a u-turn too close to the steering lock.