My reasoning for going lighter is so I have a flatter trajectory. I do some open ground spot and stalk every year and I find that they often get closer or farther away between when I range them and when I am ready to release an arrow at them. With the lighter arrows and thus increased speed I have one pin out to 30 yards. I find it to be an enormous advantage to not need a range finder inside 30 yards whether that be for whitetails or whatever. My draw length is also only 27". If it were 30" I could have the best of both worlds, but I am a short guy so in order to accomplish what I want I have to have a lighter arrow.

If I were having any issues with penetration I would sacrifice speed, but my current set up shoots 63 ft-lbs of KE which is enough to blow through a quarting elk and stick in a tree on the other side. I simply don't need any better penetration.