An AR is a great rifle for home defense purposes. Just take a look at the toys that uncle sam uses for CQB...
Self defense shooting distances are well inside of fragmentation ranges for pretty much all barrel lengths. This makes the AR a nice home defense weapon when using the correct ammunition.
I keep a P95 with JHPs in clip holster w/spare mag out of the safe for home protection. I won't be as ticked if it is stolen ($300 new) when away from home as many other items in the safe. I know many of you scoff at the idea of using a 9mm, but I'm willing to bet that no one is willing to volunteer to be shot at with one. It was purchased for the wife and the weapon out of the safe needs to be one that she can easily handle.
I also wouldn't be as concerned when the police decide to take it as evidence. I have a relative that was involved in a self defense shooting years ago that the police "lost" his prized .308 How many of you would like the police to "lose" your ARs? I'm not saying that this will happen, only that it has happend...