The problem a lot of coaches have with the head-and-arm is it is a risk/reward, low percentage move. Plus, most kids don't throw it right and post on the way down.
I just spent a week in Ames at the WTT and can honestly say, I did not see one, head-and-arm. I wonder why?
If SETUP properly and finished properly it can be a great move. A lot of guys in Kansas throw a sagging or sit through head and arm.