most people cant even get near 8% on a arrow tith a broadhead because no manufacturer has made them light enough to get less than 10% on the front.

how well a broadhead flies does not depend on how heavy it is, it depends on if the arrow will stabelize the the planeing effect of the broad head.

I shoot arrows that have 9% foc with a fixed blade head and guarantee that they fly bettere than any heavy head I have ever used.