But once they're inside, you also need a decisive "last resort" defense. "Inside my home" = "last resort" for me.
This is an idea that I have mulled over for many years. First, let me just say that I live in a pretty safe area. The worst situations I generally ever hear about in homes are burglaries (whether planned or just "crimes of opportunity"), some sort of sexual assault (the female saying that she woke up to someone fondling their toes is more common than outright rape), and maybe vandalism. Of course, not to say that we're immune to more violent crime. But I don't live somewhere with a lot of gang activity, violence, open drug dealing, and lot's of drug addicts or ex-cons. So, masked gang bangers with AK-47's storming into my house is not particularly likely. Unfortunately, for some of us, it might be, but that's not my situation.
To me "decisive" brings up images of something that is going to stop someone from doing what they're doing--right now. Short of a firearm, I would personally only put a Taser in that same category. Like any firearm, a Taser will only work if you successfully hit the target, but if you do, it seem highly successful in stopping someone instantly.
Pepper spray can certainly incapacitate someone strong or even high on drugs, but it's going to take a bit of time to stop them once they're hit. In the meantime, they can still get in a knife stab or fire a shot.
But, to continue, one huge responsibility with a firearm is making sure that you are using it in an appropriate situation. We probably have lot's of scenarios in our brains (the majority probably from TV and movies) but real world situations tend not to follow Hollywood scripts. A big advantage with less-lethal weapons is that you have a far wider latitude in using them, with less chance of permanent physical harm and legal troubles for yourself.
In my own situation with a home intruder, the young guy was mentally ill, although it wasn't obvious at the time. He did at one point pick up a kitchen knife but not in a menacing way. Was I afraid during all this? You betcha! Was I in fear for my life? Well...I have struggled with that because I don't think I could articulate such a fear. If I had shot and perhaps killed this guy, I honestly don't know if I would have avoided prison, let alone getting my pants sued off me.
At least with something like pepper spray or a Taser, you can hit the guy when you first encounter them, escape, call the cops, and then let them sort things out. If all I had was a firearm, the burden of decision-making is far higher (of course, in some jurisdictions, just being in your house could be a safe defense--legally or just practically--for you regardless of the other details). But it's a very heavy burden and very few of us have any experience or training to do that. I mean, it's easy when you first see someone and they have that gun raised or knife raised, but what if you don't see a weapon? What if the guy smiles and starts telling you some story about mistakenly being in the wrong house? The guy could have bloody murder on his mind, but at least outwardly, you can't claim that you knew that in court if you shoot him at that point.
Or another point, mostly applicable to the females. Statistically, you're far more likely to be assaulted by someone you know--a date, abusive spouse, obsessed coworker--than a total stranger busting in your door. That familiarity makes it difficult to pull the trigger with a firearm when the guy isn't imminently threatening your life. Maybe he's yelling and throwing things all over the room, but hasn't yet assulted you directly. Again, with the less lethal, you have a much wider window of opportunity to appropriately use that weapon get out of the dangerous situation than with a lethal weapon, like a gun. If you try and walk away and he grabs your wrist, do you shoot him with a gun? Now, ask the same question if you have a can of pepper spray in your hand.
Anyway, a bit rambling but my thoughts for this morning.