a few years back i shot a pig with a 50# longbow, 535gr carbon with big snuffer up front. at about 15+ yards i saw the arrow hit perfectly at the hog's elbow. *lots* of blood on the dirt road, hog took off into the swamps. we tracked it good, 'til the blood thinned out a bunch and it started to rain, never found the pig. terry found the broken back end of the arrow, which indicated there wasn't a whole lotta penetration.
a year or so later i moved on to a different longbow, 55#, and upped the arrow weight to 585gr minimum, with wensels up front and higher foc. that setup blew the entire arrow right through the mid section on the hog i killed this past june (100#+)
not scientific conclusions, but for me i'm sticking with higher holding weights for 3 blade wensel heads (i like that wensels and terminators are a bit narrower than snuffers) mounted on heavier arrows. if i shot less than 55# or so, i'd wanna use a relatively narrow double bevel twin blade and as much arra weight as possible.