I've not run across a case of a suppressor being used in self-defense by a private citizen. I HAVE seen a clueless prosecutor assume that a citizen with a legal machinegun must have been a bad person and therefore charged him. He was acquitted, but it was a long ordeal.
The use of the suppressor in a home defense situation is a case that can logically be made. I don't do it because I don't this it's worth the risk to me personally, but if the matter comes up it should be an interesting test case.
Your side would be wise to point out that as a legal owner of a suppressor, you've been exhaustively investigated by the US government and authorized by them to own it, and are therefore all the more a "certified card carrying good guy."
We would all be better off if the general public was more aware that silencers are legal in most jurisdictions, and are considered a gentlemanly courtesy to others when used for recreational shooting in other countries. American Silencer Corporation is working toward that, and more. Check out their organization at www.silencersarelegal.com