I've only fallen once. We were doing some intense hill climbs at Ft. Davis and at the base of a hill I felt too tired to climb. But I waited too long before clipping out and while at a complete standstill I simply fell over. Didn't even get scraped up.

I always unclip with my left foot. It's my weakest leg and if I decide to re-clip in (light turns green as I approach the intersection, etc.) or I can't get that foot clipped in, I can still pedal by pulling the right pedal up and give myself some more time. I often ride around my apartment complex with my left leg dangling and my right leg pedaling as it's just easier to maneuver that way around cars and ramps and my foot's already out in case I have to stop suddenly. I never unclip both unless I need to actually dismount from the bike.

I really prefer the clipless pedals and when I build up my steel frame commuter I'm probably going to put another pair of 105 pedals on it since I can't imagine riding without them.