I have a Connex link on my chain and a spare one in the bag. However, if the chain snaps on a ride, you're still going to have to remove a rivet or two to get the spare Connex on there. Besides, few people I ride with carry a chain tool. I'm going to be hailed as their savior one of these days.

QR wheels? Are you talking about clinchers that are easy to get on and off without levers?

The point is, I come prepared for most riding emergencies with a very small bag that doesn't poke out from the sides or back of my saddle. I'd rather have it and not need it than need it and not have it.