I have a kesterl KM40 and am thinking of upgrading to a airfoil. (mostly to get rid of the clown wheels!) but i don't want to end up slower. Anybody have any experience riding both or seen any aero data that the airfoil is an improvement? i remember some old data from softride on the km40 (which i can't find on the internet) and have seen the new kestrel adds comparing a talonsl.