On MAST, I'd be very curious if there's any research on their use as a pelvic splint -- especially in contrast to a sheet or a SAM pelvic sling.
I can't speak to research specifically, but by the time I left the field that was what we were using them for more often than anything else. Anecdotally at least they seemed to make effective pelvic splints, and were better for our long transport times than messing with sheets.