Tactically, silencers are a great idea. They protect you and the bad guy's hearing and suppress the muzzle flash. I don't actually recommend them to be used during a home invasion or any other defensive encounter because number one you're going to lose your expensive toy to the evidence locker. Number two, the NFA community doesn't need that kind of publicity. We are still allowed to buy these kinds of toys because no one has yet ever committed a crime with a legal Class III weapon.
The best reason for a silencer is it opens up more places for you to shoot. A 9mm or .22 silencer is very quiet and an indoor shooting range could be set up in your garage without your neighbors having any idea. You can buy a complete Walther P22 with the silencer and bullet trap for under $500 (picture below). If anyone needs help on where to get it and what paperwork is required in Louisiana just ask. I learned Louisiana has a few extra hoops to jump through so other internet guides about buying NFA aren't exactly accurate. Basically, if you can legally buy a gun then you can buy a silencer.
No, I would never leave a defensive encounter without calling the police. Even if just drawing on a bad guy until he runs off requires a call to 911. Who's to keep the bad guy from calling 911 and saying some crazy guy "just pulled a gun". You always want to be the first one to make the call.
CiCi's is great. Anyone else interested?
Cheap Walther silencer setup (not mine, but you can buy or rent it locally at Red Stick):