This age is really tough because, as you say, he is old enough to be responsible for, not just himself, but also young children in an emergency late at night. However the idea of leaving them alone in the house just seems wrong!
I think it is another one of those times whn you have to be sensible about risk and look objectivly at your child. Would you really trust him to get small children out of a house in the case of a fire? If the answer is yes then you should probably trust him to get himself out - of course the next question is do you trust him not to organise a party whilst you are out
I think he might be better alone too. I have strange photos on my digital camera of DS and his mates doing strange things with fruit and household objects when he was left home alone. he is older, 20, but you never can trust them. Before you go out give him the lecture about not abusing the trust you have in him. Tell him if you have any carry-on, then old Mrs Meggins from down the road will be coming to sit him next time. And her moustache.
I have a 14 yr old DS who is probably more mature and sensible than I am. I would only leave him if there were somebody ,a friend or neighbour , nearby who he could call on in an emergency and they knew about the arrangement.