John,

In your case it doesn't matter what kind of vanes are on the arrow when checking the speed out of the bow as there isn't any time for "drag" to slow the arrow down. However, down range an arrow with longer vanes (more surface area) or more offset can certainly make a small difference. I don't think you'd see a whole lot out to 30 yards though unless you "overdo it".

The statement about "pure physics" also assumes that both arrows are using the same fletching at the same angle. There are just so many variables in all this stuff.