The further down range you get the heavier arrows will have more KE, they don't loose speed as fast as the lighter arrows. At most eastern US ranges this is probably insignifcant, as in the trajectory loss for most shots around here if you know your bow and your hunting spot but once you go out west and see people launching arrows at 40-60 yards the numbers will start looking a little different. The trajectory will get you with the heavier arrows but the KE will be in their favor out that far. This is one place where momentum does matter. Pick your poison on this one.

I personally like a slightly heavier arrow because it is a little quieter, a little less stress on the bow as more energy is absorbed by a heavier arrow, and in my bows case it is more effiecient to use heavier arrows. I'm not talking 600 grain fence posts, I'm talking 450-500 grain out of a 65 pound bow. Or 450 out of my 55 pound bow.