I remember the "super hilbre" head, Ken. I never shot them, but some years ago while chainsawing a log, sparks flew. I ended up replacing the chain and cutting farther down the log. When I split the log, there was a super hilbre embeded in the log.
The theory was that with that long and slender head you would get more penetration. I used bear razorheads on those cedar telephone poles back in the 1960s, and took several deer with them; even had a couple of pass throughs. They were a big improvement over the old three blade heads I used before then. Easier to sharpen too.
These new broadheads are so advanced over the primitive tackle I used back then it is like night and day.