I have said it before, I' ll say it again.
The SLOWER the arrow...the BETTER off you are with a cut on impact head (i.e. single blade...or even the steelforce style 4 blades)
This test showes that older fixed heads failed... a LOT (sound like something said about older mech heads).
I would suspect that if done with some of the better heads of TODAY (Rocky Ti, Slick Trick, etc) you would find MUCH more favorable results.
One thing not looked at much, is the force of friction as it relates to speed.

" As long as the very fastest arrows travel not much over 250 fps" well THATS over (we still cannot GUARANTEE kills).

While an informative and well thought out set of tests, I think with better broadhead designs, and higher speeds, you will likely get different results.
While they didn' t get to eliminate as many variables as I would have liked to see...the number of arrows shot helps the accuracy of the results.

Now...next time I shoot a 94# bow at 182 fps...I know to use a cut on impact head