I have yet to find a pedal and shoe that works for me off road, so sneakers and Deore pedals w/ clips and straps. I have thought about their aspect on this fall off. Not to be contrary but I've shaved skin off my knee and hips before with clips and straps and released prematurely with Speedplay X2s. So I'm not sure I could predict crash/feet retention possibilities with any combo anyways.
When i had stopped I stayed still just sensing my body till I was comfy (bad non pun) with my state before I tried to get up. I have done this pause before but sometimes that pause was really short (fear of on coming traffic with previous bike crashes and/or fire in auto crashes).
I have to say (again?) that I have suffered with very good Karma in my bad moments in my past. I seem to fall well. Or fall with less damage then I might have thought in hindsight. Maybe my early Judo and gymnastics kick in when I need it
. Andy