Well, I DO prefer a knife in a lot of situations, mostly the ones I've been in. I can hardly find a situation where a gun would have been any better. But I've still never needed the knife. Also, most people don't have the skill or experience with a knife to be in a confrontation and NOT risk open wounds. I can't say I'm any better, even with practice.
I would rather cut someone off of me, who has taken me to the ground, than worry about a gun. I'd rather make a cut on someone who has decided to take a swing with a stick, than avoid and draw a gun. These situations require contact range, and getting out of there fast enough is difficult, much less drawing a concealed firearm. But empty handed I have less risk. My main point is, if he's alone, I don't think I need a knife. If I have to worry about who's next, I'm cutting him away, stabbing the next guy, and hoping I've cleared a way out. Perfect scenario, but I try and be positive.
I just don't believe it could be done the same with a firearm. Also, I'm in California and don't have that option.