This pretty much hammers in the nail. Different types of situations demand different types of tools. I would use a Dremel with a cutting wheel if I wanted to fit a length of copper pipe to my specifications, but I certainly would not use that same rig to, lets say, remove a bit of extra solder from a circuit board.
To answer the OP question, there is NO such thing as "too close", because in many SD situations, it is the perp who chose to victimize you at that point in time, whether it is a robbery, or kidnapping, rape or attempted murder, and he/she may come in real close to you, or stay some distance back and use a baseball bat or other type of weapon. Bottom line is, we did not choose this battleground. Someone else chose for us and it is up to us to respond using the right equipment, if we want to make it out there in one piece.
Personally speaking, once a situation turns into a contact range fight, a firearm is pretty much out of the question. For one main reason. Remember what we have been taught in basic gun safety and maintenance regarding BORE OBSTRUCTIONS? A fragment of wadding remaining in a barrel have destroyed many a fine hunting rifle and injured their operators. Now in an SD situation, the perp's body would have become a bore obstruction. There is simply no telling just what will happen when the projectile and all of it's hot propellant gasses are fired into a blocked barrel. Perhaps the bullet will enter the body of the assailant, do it's work and save your life. Or the barrel may explode in your face and shower you with pieces of metal, if the barrel already has a latent undetected defect in the metal from the finishing process. Perhaps the barrel may simply bulge. Nonetheless you are now holding a ruined weapon and if there are multiple assailants, you are screwed.
That is why, for the possibility of confrontations that may turn into a life or death grappling match, I always have a tactical folding knife as part of my EDC kit. Preferably one that has an assisted-opening mechanism with a finger activated switch. I have several of these. Schrades, Smith & Wesson and Black Legion. With blade lengths varying between 3.5 to 4 inches and sporting partially serrated cutting edges. Most of these are either linerlocks or framelocks and are built like tanks. Even without the blade being deployed, the knife can be gripped and the swivel part of the frame used as a pretty nasty and effective blunt impact weapon. Knives are not just weapons. They are also tools, and I believe I never, ever walked out of the door without having a tactical knife, flashlight and a trusty Zippo as part of my belt. Guns? Depending on the laws in the area I am in and on the nature of where I am going to. Sometimes I carry, sometimes I don't. But a knife has always been part of my kit.
