I own multiple suppressors; but none of my home defense firearms are suppressed for the following reasons:
1) If I am using lethal force, it is a matter of life and death. I want my neighbors to hear gunshots. I want people to call 911 in the event I am unable to do so. A suppressor reduces the number of neighbors who are likely to hear gunshots and call 911.
2) From a psychological standpoint, I want the person I am shooting at to feel as though Thor himself is hurling thunderbolts at them. I want them to feel the wave from the muzzle blast, have their ears ring and see white spots from the muzzle flash. That is a fine line to walk though since I don't want any of those things to effect me
3) I live alone with multiple dogs so a suppressor doesn't help me communicate with a spouse or children or help me identify "good guys" vs. "bad guys" who might also be shooting.
4) A suppressor adds length and bulk that I do not need in that situation
So just from a tactics perspective, those are the reasons I do not use a suppressor on my home defense firearm. Sometimes I think people who think about a suppressor for a home defense firearm may have been unduly influenced by Hollywood and think they are going to stand in a dark corner and stealthily eliminate their invaders ninja-style; but the truth is you'd need a really big house before even a suppressed .22LR with subsonics wouldn't be immediately noticeable by the person you were shooting at.
From a legal perspective, if you get in a borderline self defense shooting where you end up being charged, a suppressor is really unlikely to help your legal defense. The best case scenario is that you can educate your defense attorney, who in turn can make a good argument with the help of an expert witness.
Having said that, you have to understand ANYTHING is going to be used against you if you end up getting charged. If you trained too little, you're negligent and dangerous. If you train too much, you're a Rambo-wannabe just waiting to shoot someone. There is no Goldilocks level of "just-right." So you can't make decisions about how to handle an immediate threat of death or serious bodily injury based only on what a prosecutor might say if he disagrees with your view on the necessity of lethal force.
I would advise people to sit down and give some conscious thought as to why they want to use certain equipment. What benefits does it offer? What are the risks (which includes not just the probability of an event; but the consequences of a rare event)?
Do you shoot better with a suppressor because the lack of noise and flash makes you less flinchy? How much better? Get out there with a shot timer and evaluate it. Better yet, document it in your shooting log.
Do you have a spouse who is armed? A suppressor for both of you might help distinguish their shooting from bad guys shooting and will aid in communication between you and any other household members.
Are you living in a meth lab where flammable vapors are an issue?
You get the idea though... evaluate the benefits, consider the possible negatives (IF I get charged, I'll at least need to fork out for an expert witness and an attorney who can present a good argument) and decide for yourself if the juice is worth the squeeze in that situation. A real good way to test this is to talk to your spouse/friend/family - someone who knows you well and knows what you own firearm wise - and explain your logic to them. If they look at you like your crazy, then at a minimum, you know you need to work on a more convincing argument for that plan; because a jury is not likely to be kinder to you.