I personally suspect using a NFA item in self defense would make no difference if it was a 100% "clean" shoot. In such a situation the media would likely would say next to nothing about it because they would not want the public to hear anything positive about NFA items or about NFA owners. However, if it was a situation where it was less than 100% clear cut that you were in the right it probably wouldn't help your case any and the media would most likely be all over it. Personally though, I would use a NFA weapon for self defense without hesitation in your hypothetical scenario of armed intruders and a NFA item being the closest viable option when I felt my life was threatened. I surely am not going to worry about whether or not the tool I need to use for self defense is politically correct or what lawyers may or may not do with it. Live first, worry about the trial later. Like I said though, as long as it is legally held, and the shoot is clear cut self defense(ie: robbers are found dead in your house and you didn't do anything stupid like shooting a unarmed teenage thug after he ran out of your house or your neighbors house and is half way down the street with the stolen goods.) I don't think you would have anything more to worry about than if you had used any other gun.