I seem to have bad luck with motor braking enabled and belly landings taking out my prop. What are the odds of seeing your prop stop vertically, bumping the throttle only to see it stop vertically again? That happened to me last weekend. What was the end result? Half the prop cracked just before the hub.
That was an 8x4 on a small foamie "Fast and Furious" plane I was getting ready for a combat event this weekend. I mostly set the motor brake on so it would glide better on landings.
My versa wing, initially had motor brake on, but the motor I had didn't really do any braking until it dropped down to about < 4 meters per second... so it was kind of useless, I actually prefer the free wheeling prop on that one because it glides too darn well, when I want it to land. So, now, I have it set to freewheel to add drag.