I wouldn't want to leave home without a chain tool. It's rare, but a chain can just break and I want to be able to put one together to get me to the next bike shop.
Personally I do carry a multi-tool, with chain-tool, because I prefer to do my own work and I'm cheap. Chains rarely break < 1500 miles. As I said stop at a shop every once in a while, change them out. In addition
SRAM power link needs no tools.