I've done it twice:
I exclusively clip out with my right foot. The one time I decided to give my right foot a break and unclip with the left I lost my balance and fell. I think you intuitively get accustomed to shifting body weight to the side you typically unclip, so be cautious if you want to be an ambidexterous dismounter! The other was while learning a very important lesson about riding with a flat... flat tires don't roll as easily at inflated ones. With a puncture, ALWAYS unclip prior to applying breaks, as the bike will stop quicker than you think!
On a humeruos note, I really enjoy the little jig people do on their pedals when they lose their speed and realize they're going down. I was riding with a friend once who was showing off in front of a convertable loaded with women. While he was showing off his balancing act waiting for a light to turn, he lost his balance, did the jig and went down. Too funny.
MC