You show me a system that can guarantee I won't get cut in a knife fight. How about one that even will give me a "high" percentage of not getting cut. I have seen some that seem like they are much better then most.. but honestly...
I would rather just give someone my wallet. When you get held up by someone, you will understand. I have been approached were they didn't seem to have any weapon and I have had someone pull a knife. I gave the guy my wallet without even thinking. It takes very little skill to kill someone with a knife, even the smallest knife.
I have had this discussion with Kali "masters", seals, and even special forces people. I even talked to a few Israeli arm guys. I have yet to train any knife style because I'm not impressed.. again I'll give someone my wallet faster. HELL I carry a fake wallet just for that reason.
Isn't martial arts about keeping yourself safe and using your common sense?