In my experience; and I've shot game 2 blade, 3 blade, 4 blade, replaceable blade, expandable, single and double bevel; I do like the single bevel and think they do exactly what they're professed to do. It does seem the "s" shaped entry hole and spiral wound channel does result in good blood trails - but like said above, so does any sharp, well placed broadhead. I'm not convinced there's a huge advantage to a single bevel, but will continue to shoot them and test them.
The "S" shaped cut is obvious on the hide, and also on the side of a new, fresh 3-d type target. I shoot a rhinehart 18-1 target and the single bevel heads do leave an "S" cut on the target and do spiral through the target.