No falls this year with SPDs. Two bad ones last year, on regular pedals no less, and at low speeds. Have yet to bite it with clipless. Actually, now that I think of it, I fall more often while on foot than on bike.

Sometimes you just have bad days. I've used retractable knives every day for almost 4 years with my job, but I managed to slice a meaty chunk off my finger a couple weeks ago.