I've been using this app and really like it. To get a good score, you really have to brake. It's $30 but well worth it. I find it accurate and consistent....and consistent with the 3D Biomechanics info we've all been reading around here.
Thanks Mike, seems worth it for a 'poor mans' K-vest!
I notice from the screen shots they are recommending an 'Ideal Peak Time To Impact' which in the first case is recommending to your subject to reach his hip max speed a little earlier in the swing. (0.12s before impact as opposed to his current swing which reach max speed at 0.05s before impact.)