8000 miles in my first year of road-biking on Ultegra SPD-SLs. Probably well over a thousand stops and have never fallen. You're right about complacency - after a 70 mile ride I was exhausted and unclipped my left foot as usual at a stoplight but turned to look at something to the right. I started falling right and STILL managed on the way down to pull my right foot out and not fall. I did have a lovely groin strike on the tob tube in front of 100 people at the beach but at least my no-fall record is still intact!