I've never had the displeasure of making that decision at home. But I've been on the wrong end of a deadly weapon enough when outside the home. While I absolutely will defend my home to whatever extent is necessary, you have to realize that taking a life is HUGE. It's not fun like some might think. That power rush and adrenaline goes away very quickly.
This is just my experience. But there are faces and images I see every night when I go to bed, and likely always will. Take it from someone who knows, lethal force is serious business and if you're going there first, it sucks to be you.