I've recently dumped my bike twice while clipped in and I've been using clipless pedals for years. Each time I came coasting to a parking area consisting of gravel or loose sand. I was duly careful and unclipped my right foot well before I needed to do so. However, as I came to a stop the handlebar jerked to the left, my left foot was still clipped in, and over I went. Just something to watch out for.