While I never got into an accident, my experience with the non-multirelease SPD cleat with M520 pedals is the same as recursives. I pulled out during hard sudden sprints, during hard leg slowing/skidding. I could even pull straight up with leg while stationary on stand and pop it out if cleat had ~200mi of wear (with lots of short trips due to commuting) with new pedals set at max. release tension.

I got ATAC XS pedals and have never clipped out.

Al