My friend's sister and husband were home invaded by some Mexican illegals. I know that because 1 was caught and rolled over on the others. They picked up 3 of 4 remaining and 1 made it back, presumably, to Mexico. I believe the case is still ongoing, so I can't provide too many details.
I will say that he had a rifle, but it was upstairs somewhere and not accessible. The invaders came in all swat-like and totally took them off-guard. Even if he had a military or police trained dog, he probably wouldn't have had time to get to his rifle and attempt to fend them off.
It's a really horrible story, but needless to say they are both well-armed these days and practice a lot. You can call me paranoid, but when I'm home my XD9 rides on my side at all times or isn't very far away. I certainly hope that the other poster is right about the slim odds of a no-knock warrant being served at the wrong house because I will most likely start shooting if anybody kicks my door in and points a gun at me.