I dont think it has to be sharp its just cutting a path for the body which isnt that large, once the blades deploy they do all the cutting. A chisel that cuts stone is not sharp but still cuts something as hard as granite. The finer the edge the more prone to chipping or breaking, just my opinion. If it really made a big difference they wouldnt do as well as they do, right?????

Unless it saves them $$$$$$$$$$$$$$$