I have tried both with little difference. I use helical because thats what the clamps for my jig are. I borrowed straight clamps from a friend to try offset. We both use Jo-Jan fletching jigs. He is always borrowing my helical clamps for his feathers. I like the look of helical better although they flew the same or I should say that with my skill level there was no noticable difference. A better archer may be able to tell.