Probably irrelevent addition to a very full, informative and amusing thread
But for what it's worth
I'm recovering from a broken leg, after a sideways fall on a very slippy road at a very low speed. I was wearing SPDs.
BUT - I knew it was slippy, had unclipped way before the tight U Turn, and still tumbled faster than I could react
What's the point of my post? Just, the clips might not be the deciding factor. Stop, dismount, pick up and replace the bike 180 degrees if you're on a surface you couldn't run fast on
Stay safe, all