So, you'll often hear people say that it's better if a burglar you shoot in self-defence dies rather than lives.

This is exceedingly dangerous advice, to be frank.

First, in self defence you MAY, depending on circumstances, be permitted to use potentially lethal force. That is not the same as intending to kill someone. At the point where you're intending to kill someone you're into some serious criminal offences. Also, you could seriously fuck your self defence argument. You're also talking about relying on perjury to establish your self defence argument at that point, which makes you no longer the hero of the story, just another villain. You should not bank on being smart enough to get away with lying to the court.

Further things to note: I have had a file where someone shot at an intruder, but didn't hit the intruder. The file was approximately one inch thick when printed out, and the Crown ultimately killed it long before it went to trial. The charges were pointing a firearm and assault with a weapon, which in the scheme of things is not the most serious. I have had files where an intruder was shot and hit. The charge there was aggravated assault, which is quite serious, along with pointing a firearm. This one was also killed by the Crown before it went to trial. In both cases they had an available witness (the burglar), but for fairly obvious reasons the burglar isn't likely to be held to be the most credible.

I've also seen disclosure from self-defence killing investigations. As an example, one such file was ten three ring binders worth of paper, plus about ten hours of video.

Even if the Crown kills the charges early, you are paying for a lawyer to go through a ton of material. Expect your legal costs to go up at least five-fold, and likely substantially more than that. The burglar may have been there to steal your jewelry and tools, but you may well have to sell the entire house to cover your legal costs.

"But if he lives, he may sue". And if he dies, his next of kin are very likely to sue. As was put in the film Ripley's game: "Even bastards have friends... even dead bastards." And I can guarantee you that the wife, or mother, father, or the like of a dead burglar is going to be determined. They'll be calling the Crown on the regular asking why charges aren't being brought. They'll be contacting lawyers to sue. By contrast, the living burglar who merely got shot (or shot at, or scared off) is probably not terribly keen to show up for your trial.

"But now there's no one to testify against me". Well, no. There will be a veritable army of police investigators, forensic examiners, and so forth. All of whom will come before the court and look very professional, very honest, very earnest. You know who won't be there to point the finger at you? The violent junkie who was breaking in. If you're thinking this one through, though, this guy being there might be a strong thing in your favour at the trial. He gets to squirm on the stand as he tries to explain what he was doing in your house, and likely lies about it. It can be way better to have some sleazy dirtbag blaming you than not. Alive, he gets to be in full view, and you can cross-examine him on his faults. Dead, the jury is going to see his best moments, along with his autopsy photos, and it's hard not to feel sympathy when you're looking at a guy on a slab.

And remember that difference in file size? That's because a dead body opens up all sorts of funding doors. With a live victim they're not going to bring in a blood spatter guy, or crime scene reconstruction guys, or various other experts. They're not going to do things like go, "Well, that knife that was in his hand, let's look at fingerprints. Let's talk to our expert who has studied the signs that a knife was planted on a dead body. Let's have a million different experts checking every single detail of the story to see if it matches up." Instead, the Crown will probably just rely on the evidence of the aforementioned skeeze.

As I mentioned before, if the guy dies, the stakes go way up. Manslaughter is a much worse charge than aggravated assault. Second degree murder is worse still, and has a minimum sentence of life in prison. A conviction for second degree murder will change your life forever. A conviction for aggravated assault will screw your life up for years. A conviction for pointing a firearm is bad, but your life will go on. Note that this can shift a bit on a civil suit, because a guy who is disabled and unable to work is going to have greater damages than a dead guy who had no work prospects... but this shouldn't be the focus of your concerns.

Also note that your self-defence argument is strengthened by you doing everything possible to keep the guy alive. Let's assume you had to shoot a burglar to preserve your own life. Your argument at trial will be vastly stronger if you have done your best to bandage wounds, staunch bleeding, called 911, and so forth. Your argument at trial will be much weaker if you sat there and watched him bleed out. You want/need every moment of the interaction to be one where you are beyond reproach. You want to be telling the judge and/or jury a white hat/black hat cowboy story, not a story where everyone is shades of grey.

You should also consider the impact on you. Everyone talking about self defence on the internet plays it off like they are John Q Badass and will be completely unphased by killing someone. Well, research shows this is probably not the case. Police officers in justified shootings have all sorts of nasty potential mental health sequelae. Same goes for our soldiers. The effects on civilians (you) are likely worse still. The risks of suicide, family disruption, and other nasty effects go way up.

Also worth noting: If someone dies, expect that the police (and possibly the family of the victim) will be doing research into you. You should assume that any comments you make about how it'd be better if an intruder was dead rather than alive will be found, and realize that neither a judge nor a jury would view them very favourably. Having to explain that sort of comment would make for a very, very unpleasant phase of your cross examination.