The single bevel broadheads do a great job, but then so does any other sharp broadhead.
When asking about blood trails with a broadhead, there are so many things to factor in that there honestly can't be a "generic" answer. Shot placement, state of the animal, all play a role in what kind of blood trail is left for us to follow.
With all that said, one big advantage of the single bevel heads is their ability to go through bone. On a deer last year, I had a Grizzly enter in a shoulder blade and exit through the lower end of the other one.
Thanks,