RE: 4 or 5 inch vanes?
Hell, I shoot 2 7/8" vanes (Kurly vanes) and 1 1/8" 4 blade heads (Slick trick) I get the same point of impact with my FP as with my BH to 40 yars (as far as I have tested).
Oh yeah, I don't align heads with fletch, and I shoot 29.25" arrows.