I've fallen three times, but never as a result of clipless. The most recent was on the way to work yesterday morning. The first two dozen patches of ice were no problem. The 25th is where I slid--only until I ran out of ice. Then, when the tire bit into the asphalt--at 45° to my line of travel--it pitched me over the bars.

My first thought after crashing is always, Wow! They really do unclip in a crash!

And FWIW, I highly recommend the tuck-and-roll method for the unplanned flying dismount. The end result is so much better than the slam-down-and-skid-across-the-pavement method I've used in the past. Third time's the charm, I guess.

Back on topic...

What did it for me is that the owner of my LBS is a great coach. After we got the pedals and cleats mounted and adjusted, he took me out to the parking lot and demonstrated the proper method of coming to a stop, unclipping and putting your foot down.

He watched me go back-and-forth, doing stop-and-go drills for five minutes, then told me, "Do that for another half-hour, then come back in". He checked on me a couple of times, made some corrections, then after that half-hour, he gave his permission for me to ride home.

I'm grateful for that early do-it-'til-it's-automatic, then do-it-well-beyond-boredom training. I'm absolutely certain it's the reason I've never had a clipless fall.