I have the RD-4, Afghan, and the RD6 Sinature series, an RD Hawk, and a couple of Ontario machete's. I really want to like them, the RD-6 is thick, sharp as it can be, and sure it might cut thin slices of paper, but try a fish or a carrot. When the entire thickness has to pass through the material, it's a different matter..
I have spent lots of time reprofiling the edge of the Afghan, and the RD-4. I re-shaped the handles with sandpaper, cause the caused pain to use otherwise. The handles are so blocky, that if I just squeezed them hard, I felt pain. Hard use, well, lots of pain. Not a deal breaker, sandpaper is cheap, and the materials are great. The time I spent on the handles and convexing the edges, machete's as well, was quite a bit. For me, it was gathering some skills for future knife making. For others with less time or patience, get one from Justin his knives have better F&F.
On to the 5160. I didn't think much of the HT from Ontario, it's "soft", so very tough, but dulls fast. By comparison, I also have a Culberson Bolok that was shaving sharp, and after a few hours of hard use, chopping hard seasoned wood, it was still sharp. I can tell a degration in minutes of use with my other Ontario's.
All in all, you get what you pay for. Uneven edges, crappy sheaths, the RD Hawk's sheath is okay, blocky handles and a softer HT. The are strong, I use my machetes for yard word, and the Afghan chops through roots, digs, can be used hard and pryed on. Just don't expect great F&F, or excellent slicing.
I'm not putting them down really, just being honest. The are American made, and tough, anybody can re-shape handles, rework the edges, and get a better sheath.