[/quote]
do not believe that Norb Mullaney ever said that efficiency goes up when you put on a lighter arrow. If he did he was incorrect. You could put on a lighter arrow and increase KE if you also made some other change to compenstate for the loss in efficiency. For example increase draw weight or lower brace height.
I'm can't remember his exact wording, so if efficiency is not the correct term then I'm open to a better one.
But............ the fact remains that there are bows that will shoot a lighter arrow with more KE than a heavier arrow under the exact some shooting conditions; i.e. same bow, same draw weight, same draw length...only the arrow changed.
I've seen it and so has he.
Now as to the merits of KE vs M........I think its a much belabored, over emphasized debate that is only an issue with the most marginal of equipment or the largest of game, neither of with which I'm likely to be confronted.
Generally,however, I subscribe to the Arthur P philosophy. I leave my just for play hot rod arrows by the chronograph, and my heavier work arrows in my quiver.