I agree everything needs to be taken into consideration. Along with a good weight arrow you certainly should be shooting a broad head meant for what you are doing and they should fly straight. I just sort of figured that as a given. I never said you couldn't kill game with a lighter arrow, I am merely suggesting that a heavier arrow would perform better. If you ever shoot a deer and don't get a pass through and have a tough tracking job chances are the heavier arrow probably would have accomplished that for you, providing you had proper shot placement.
Most don't consider 400 to 500 grn arrows heavy either.
My bow shoots a tad over 200 fps with 450 grn arrows and I don't need more than one pin out to 25 yards which is all the farther I care to shoot at deer. Oh, and my bow has an IBO spec of 324 fps (bowtech mighty might) so it's plenty efficient, I'm just little is all. I used to shoot a bow that was less efficient with arrows around 350-360 grns. It worked, but once I upped my arrow weight I noticed better performance on game at hunting distances. And the better bow just makes it all that much better.
I personally have no desire to shoot over 250 fps. If had a more efficient bow, or longer arms
that would let me shoot 280-300 fps I would most likely up my arrow weight until my speed came down to around 245-250 fps.
If you want to disagree with decades of experience and testing feel free, you are welcome to believe what you want. However like I said before, to those of us that know better you won't change our minds. Just because you don't think you need a heavier don't try and make us believe it wouldn't work better because we know it will.
A really simple example of this is my kids little plastic recurve bow. If you use really light youth arrows it won't stick in my back target more than half the time. If I grab some of my heavier aluminum arrows (400 grns) it will consistently stick in the bag. The light arrow might get there a bit faster, but the heavy arrows retain more energy and momentum to the target letting them work better. Both have the same energy out of the bow, the heavier ones just retain that energy better.
Paul