Dave, I am curious as to why you believe adding a heavier head makes the arrow more prone to breaking behind the head. Has that been your experience?
To my thinking, a heavier head moves the FOC forward. Since the FOC is actually the center of mass, you end up with a distance between the center of mass and the broadhead which is shorter than before. Since a shorter shaft (of identical spine) is stiffer, to my thinking it would be a little harder to break, not easier.
Maybe I'm all wet. I'd like to hear your thoughts and experiences on that. I've not had any trouble breaking woodies with heavy points, but in all honesty I'm not real hard on arrows and seldom break one.
I've been fooling with one of Andy's internal footing jigs lately, another interesting option.