LOL! I keep arguing it because so many people insist on misunderstanding it.

The point is, one CAN achieve great penetration with ultralight arrows (wich I define as 6 grains or less per pound of draw weight)... IF they have the capability of driving them fast enough. Also, as you so aptly point out about the variables, IF they are very good at tuning their bow with those fast arrows. IF they are good enough shots to place those fast - and often rather unforgiving - arrows in the correct spot. But to get momentum equal to that 700 gn/150 fps arrow, they're generating more KE than old time bowhunters were using to kill elephants in the 50's and 60's. Back then, a 45 pound recurve was the most widely favored deer hunting bow, which might have been giving a whopping 25 ft lbs of energy with wood, fiberglass or aluminum arrows.

For someone shooting low poundage, low performance bows, like those ol' 45 pound 'curves, they can still achieve excellent penetration without gobs of KE simply by increasing their momentum. The light arrow guys increase their momentum with high draw weight/high performance bows to zip those arrows along. The guys with the low performance rigs need simply increase their arrow weight.

That deal about carbons flexing less when they hit, that bugs the snot out of me. First off, I definitely agree you don't want your arrows flexing at all because they're wasting power by flexing. However, considering the average deer's chest cavity is less than 20" across, even an arrow going 150 fps is going to be through the deer in only 1/100th of a second. It won't have time to do any significant flexing anyway! Even if it did, have you ever considered that sometimes it might be a good thing to have an arrow with some flex to it? Like if it hits the edge of heavy bone, it can flex and slide around the bone rather than use up much more of it's power trying to punch through it.

Hey, as far as you talking carbon arrows vs heavy arrows - like carbon can't be heavy - you wanna try one of my GoldTips that I've got weighted up (stuffed with aquarium tubing and weedeater line) to around 750 grains? I bet they'd make your target holler hidey-ho!