I have a multitool with a chainbreaker in the saddle bag of one of my bikes; I got a tool with that feature because I'd seen way too many group rides come to a halt because someone didn't have one...and I've seen that halt shortened appreciably on 3 or 4 rides because someone did have one.

However, having said that, I've never had to use my chainbreaker tool...which I guess is why I only have one in the saddle bag of one of my bikes rather than all of them.