I've read most of the thread and there are just a few points I'd like to address. That said, it's early and I'm pre-coffee, so please bear with me while I ramble a bit.
1. Affirmative Defenses -- as a general rule, the party asserting an affirmative defense has the burden of (affirmatively) proving it. IOW, if SD is an affirmative defense in your jurisdiction, it will be on the SD Shooter to prove that his or her shooting of another person was, in fact, an act of self-defense. If the prosecutor has to prove that the act was not SD, then SD isn't an affirmative defense in your jurisdiction.
https://www.law.cornell.edu/wex/affirmative_defense
2. IMHO, the real problem with using a suppressor on an HD weapon is not a legal one. It's a jury perception problem. I think the modern media would call it 'an optics problem.' Right, wrong or indifferent, the American public thinks that suppressors are assassins' tools. In my jx, suppressors are completely legal, so I'm not worried about the
legality of using one. I note, however, that if I shoot someone, and the Prosecuting Attorney doesn't buy my (incredibly honest and forthright) tale of how it went down, a jury really could allow that suppressor to cloud its view of everything I did, and everything I said.
3. The prosecutor doesn't have to spend a lot of time talking about the suppressor to make #2 happen, either. If I were prosecuting it, I'd have a photograph of it blown up. In particular, I'd want either one of it next to a ruler, or one of the gun next to the little sandwich-board-looking evidence markers. That way the jury knows it was photographed at "the scene of the crime." I'd put it up in the jury's view during my case in chief and basically leave it there as long as defense counsel would let me.
4. Even knowing all of the ways in which using a suppressor for HD could go wrong, I'd still use one if I had one suitable for it. Personally, I think some subsonic .45 ACP would work just fine. I'm 50 and concerned about my hearing. And it's not just my hearing. I'm concerned about my wife, daughter, 2 cats and a dog. I don't want to deafen any of them, either, and I'm perfectly willing to tell a jury that.
As an aside, a State Trooper in this area had someone break into his home a few years back. BG tried to come in through the bedroom window while Trooper was asleep. Trooper shot & killed him. I heard it freaked the Trooper's dogs out so bad he had to take them to live out in the country for months before they settled down. Next time I see that trooper, I need to remember to ask him about that to see if he'll confirm about the dogs.