I still have some of both laying about. I found the MA3 to be very difficult to sharpen and in the end relegated them to small game.
The Hilbre was (is) an interesting head. The razor type insert slid into the plastic body from the front. They were not designed to be replaceable. I never saw a four blade version.
My wife shot a deer head on with a Hilbre in 1970. The hit was dead center in the throat and cut a slash vertically about seven inches sliceing the windpipe and artery behind it. The head buried in the spinal column and then the arrow along with the plastic body bounced straight back out. The doe expired quickly. When I started field dressing it for her I was bewildered as to how she had killed it since I did not immediately spot the throat wound. Then I found the arrow laying on the ground. It had bounced back toward her shooting position by about ten feet.