I think it is important to train with your weapon of choice, if you seriously plan on attempting to defend yourself with it. I had to take a bunch of hours of classes in order to get my conceal and carry permit. I go to the shooting range almost every day, I train with guns now more than I train BJJ. Quite frankly, I would carry an automatic pistol (like a tech 9) if I could (of course I would also carry a pistol for better aiming because sometimes automatic pistols tend to 'ride up' as you shoot). It is important to know the gun laws in your areas, as someone pointed out in another post. If someone takes a swing at you or brandishes a knife, that doesn't give you the go ahead to just reach and blast (it should, but America is a society run by greedy lawyers).
I will often ask my new instructor about grappling with guns if the situation presents itself and his philosophy is that you need to take away the danger of a street confrontation which means working really tight and not giving your opponent the chance to grab his knife or his gun. So, if you decide to attempt to take the guy out without a weapon, you still need to be careful because even an untrained guy could bite you or poke you in the eye or something. Stuff like trapping someone's hand bettween your legs is probably not a good idea in a street fight because your balls are right there. I've been thinking more about using knives but what if the guy you're fighting has aids or something? Do you really want to get his blood on you? If I get tackled, I'm going to try to use my guard to create space, kick away, shrimp away, and throw up kicks, and I'll basically try to create space to unholster my gun so I can fire (or annouce that I will fire) from a prone position.
You could also join your local milita or gun club, they have good advice about protecting yourself and your family. Many people advocate keeping your weapons in a safe but I disagree, because if someone breaks in you have to have that shit close. Get a good alarm system and use one of those bike locks to lock your gun up close to your person if you have kids (that way if they come in when you're asleep, they won't be able to run off with your gun or something). Some companies offer remote locking doors, you could put those on your kids' bedroom doors if you have kids, you can program them to lock if your alarm goes off.
So, in closing, in a street confrontation if I sense that there might be escalating danger, I'm trying to create space so I can open those lines of fire. Five times out of ten, if you pull a gun people are going to take off anyway, you need to train for those other five times.