Ah if we only lived in a world where everything was black and white. Wouldn't things be simpler then? This is right, that is wrong, this is good, that is bad....(How utterly boring
).
As the old saying goes, "there is more than one way to get to Chicago" (or there is more than one way to skin a cat). I think when one gets to a certain level you start to split hairs. If one guy is shooting a 400 grain arrow at 270 fps and the other guy is shooting a 600 grain arrow at 190 fps, assuming both put it in the boiler room which deer will be deader or should I say more dead (Is deader a even a word? <img src=icon_smile_blush.gif border=0 align=middle>)? By the same token if you make a bad hit with either, your in trouble.
I wouldn't argue physics with anyone. I'm not smart enough for that. I couldn't tell you the difference between a time unit of momentum and a foot pound of kinetic energy. I just know both have to be delivered to the right spot to be effective. As wild Bill Hickok once said, "Fast is fine, but accurate is final..."
I love to play. I have tinkered with heavy arrows and with light arrows. I guess I fall somewhere in between in that gray area. But I have found that both will work. You have to decide what type of combination works for you. Kind of like shoes, there are all different kinds and sizes, you have to pick the pair that fits you.