RE: What shaft material do you currently hunt with?
About kinetic energy...the arrow has very little to do with KE if the setup is exactly the same...it has more to do with the bow and the energy it is able to give the arrow upon the shot. KE will vary only slightly between 2 arrows of different materials. This is a common KE equation used by bow technitians to give kinetic energy...Total Mass of Arrow x the velocity squared...divided by 450240. This will give you the delivered foot pounds of that setup. Just try and find your "happy medium" between speed and arrow mass. But, having said that, the two arrows may appear similar in initial KE (when their velocity is measured through a chronograph at 4 to 6ft), but the lighter arrow will loose energy quicker than the heavier arrow as the shot becomes longer.
An added note...shaft material will have a lot to do with how the arrow retains that energy upon contact with the animal. Aluminum will take longer to recover than a carbon will. Carbon recovers very quickly and drives deeper due to more retained energy after recovery. A great example is look at how much deeper carbon penetrates 3D targets than a comperable aluminum (with similar diameter) shot from the same bow at the same distance.