Samhain, my limited knowledge on the Karambit is as follows:
I had a fellow soldier who carried one, and was instructed on how to use it, for several years. However, the knife has but one useful purpose; to intimidate & maim your attacker. Now, granted thats a good thing, provided you are being attacked, but the knife isnt practical for really anything else. And, LEOs could get sketchy over it, as it is an intimidating looking tool, which, again, only serves one purpose. They may question you as to WHY you'd carry it. IMHO, the more invisible you are, the better. The karambit doesnt keep you below radar.