OK guys, here's the scoop on the Razorbacks. They been around for years. Originals came with five blads and weighed 142 grains. Later they came out with a four blade package.
You have it a little backwards about penetration loss though. The blades are molded into a plastic cartridge that slips over the ferrule and is held on by the screw-in tip. It's not that the blades spin on the shaft. They freewheel so to speak. There is less energy lost to getting the blades to spin against the air, and when they hit an animal there is less energy lost getting them to stop rotating. The arrow shaft spins but the blades freewheel. You get what I'm saying?
The other thing about them is that the five blades are lower profile than other fixed heads of that era so less chance of windplaning. And because there were five blades they maintained a decent amount of cutting surface.
I recently sold some to a guy who was looking for them. I had some around here for I'll bet 15 years that I never used, simply because I went to lighter heads.
One downside to them is that the blades were thin, .020 if I recall right. Bone could chip one fairly easy. The other upside is that there were a lot of other blades to finish the job. They killed what I shot with them. That much I know.
I still have a couple around just for old-time sake.
Hope this answers some questions