In my opinion, if you were given the same cutting diameter for both, the shorter length broadheads (steeper angle on the blades) can be known to stretch the hide more and create a slightly larger hole that the measured diameter. A longer head means a longer cutting surface but since the angle isn't nearly as aggressive it also slices through the hide rather than chop a hole through it. This to me would increase penetration, however I would say that it would result in a hole not much larger than the measured cutting diameter.

As you start increasing the cutting diameter for both the pro's would be larger holes which in turn would give you the impression that it would also mean better blood trails. However the trade off is that tuning issues in your equipment become more evident in your accuracy between field points and broadheads as well as environmental effects such as a crosswind. In my opinion a longer head vs. a short one at a larger cutting diameter would react more negatively to these issues since you have now increased the surface area substantially which can actually steer the head.

Hope that makes sense....