RE: cut-on-impact broadheads???
A tip like a Muzzy will break up bone better and create a larger hole in that bone for the blades to follow through thus saving the blades for the insides and creating a hole for the arrow to follow with minimal friction. A cut to tip will have to slice through the bone which does not create a broken up hole which in turn creates more friction on the shaft of the arrow and slows penetration.
Now, if no bones or just a rib are hit the cut to tip will have an easier time getting through the soft tissue inside the animal. Where an arrow will have to use its energy pushing a muzzy style tip through the soft tissue a cut to the tip will effortlessly slice right through.
It's a trade off.
Shooting through a whitetail deer it really does not matter. It does not take all that much to get through one. Shoot which ever one flys the best for you.