The empirical test will be when you shoot the guy, he falls down and is not killed. Then a person stands over him and shoots him in the head while he is yelling I give up.
Unfortunately, little Billy has told the officer - Daddy shot the man when he said "I give up". Forensics determined that he was shot in the back, fell down and dropped his gun. Then, you stood over him and fired the fatal shot as he was unarmed at the time.
Criminal and civil risk - we will see.
I agree that if you shoot someone in the house with a gun who broke in - you will probably avoid legal and civil bullets.
However, dear friends - experts who I have heard speak on these topics suggest that you might spend $5000 just to get the no-bill.