Steve,
I've never used them, but Uncle Teddy seems to have success with them. He is talking them up all the time (but then he gets paid by Muzzy for doing that). He does seem to get complete pass through on most of what he shoots, at least on North American game. And he is always stating he only shoots a 49# bow.
I have always been a little leery of serrated type broadheads, preferring a clean cut as opposed to a jagged one. Since clean cuts should bleed better. But then knapped heads are basically serrated, and they have worked for thousands of years before steel existed.
All I can say is try them and see how they work for you. Just wouldn't suggest using them on thick skinned dangerous game. But they may work for them, wonder what Ted uses on dangerous African game? Don't recall him chasing any of them, mostly only plains game.