I hunt with 3" vanes, used to hunt with 4" vanes. You asked what the difference is .. for me and my set up it was 7-8 feet per second. I noticed no difference in arrow flight or accuracy with my broadheads, the loss in arrow weight was minimal and offset by velocity of the arrow. Not sure what 7-8 feet a second really gains me except maybe that I get a slightly and I mean very slightly flatter arrow trajectory.