Bill,
<<Are headrests good for anything?>>
-only for sleeping and crashing.
In some automotive literature, many years ago, I read that most neck
injuries didn't occur during the initial deceleration and snapping
forward, but rather when the body and head recoiled backwards without a
headrest to stop the motion.  I suspect this is why headrests have been
standard equipment in cars for such a long time now.
Chris Zavatson