In my opinion, It don't matter, seriously. I shoot my heads half with 3" & 4" feathers and half with 2" max helical vanes. The amount of helical you get with a bohning helix or AZ mini is simply nuts and since I have been fletching 2" vanes with those jigs, blazers, fusions, flex fletch ffp's, they seem to shoot every bit as well as a feathers with a fixed blade out to 30-40 yards. The FOC difference with 12 grains, the trajectory difference at 40 yards are all overstated points. I have 2" max helical fusions and 3" feathers in my same quiver with the same heads and I cant shoot at the same dot at 30 yards. For me performance is a wash, and I have tried to find a edge worth worrying about. I do know feathers are more money and fuss but will continue to shoot them along with vanes, cause hey feathers are cooler and any little mental boost I can give myself at the moment of truth all the better. IMHO