Helical aids in faster recovery for an arrow. Straight or 1 degree offset fletch have much slower recovery so your tuning has to be absolutely perfect. Helical lends to a much greater forgiveness. But it also slows your speeds a bit as well. Not so much that it really matters on close range but it is a fairly significant loss down range in comparison to straight. It does make me glad to see that more hunters are actually waking up to the sheer stupidity of the whisker biscuit design.