One point that nobody yet has considered, and it's the reason I'm considering switching to a lighter arrow after hunting with 500 + grain arrows for the last two years:

Trajectory.

I'm not talking just about trajectory past 30 yards. I'm talking about trajectory between 15 and 23 yards, where most treestand whitetail shots occur.

If you look at OnTarget you'll see what I mean. If you sight in at 25 yards like I do and use a single pin zero to thirty, the arrow reaches its highest point at about 17 or 18 yards then drops slowly until 25 yards and then drops quickly after 25 yards.

I'm dead on at 25 yards, but with my 515 grain hunting arrows moving at 257 fps I'm 2 - 2.5 inches high at 17 yards.

Now, almost all of the deer I kill are less than 20 yards, but I have shot at 25 and even 35 yards at deer. I've been hitting them about 2 inches higher than I wanted every time when they were less than 20 yards. One of these days a deer is going to duck and I'm going to spine one or I'll have a less than stellar bloodtrail because of this 2" high at 17 yards problem. I tell myself to hold 2" low if the shot is close but in the heat of the moment I usually forget and hit them a little high.

Now if I use a 380 grain arrow instead, the trajectory is a little flatter. So when I sight in at 25 yards, I'm only 1" high at 17 yards instead of 2.5" high. And of course like everyone else said I'm more accurate at 28, 29, and 30 yards because there is less drop.

I loved the penetration I got with my 515 grain arrows moving at 260 fps. Ive blown through every shoulder and leg bone I've encountered on quartering away shots. But it's definitely overkill for whitetails, and I can certainly see the benefits of a lighter arrow as well, even though I shoot mostly 15 - 25 yards.