I have a multi-tool for my Tern. It is good as an emergency tool and I pack it in the seat-post bag. Because of their compact nature however, sometimes it can be hard to get a good angle for hex heads that are in odd places (like my fender mount screw on the interior of the frame). So at home I tend to use regular-sized tools as it is just faster. In the case of Tern, they sold a multi-tool that fit all of the various sizes of hex heads and bolts on their particular bike. So it is pretty convenient to have. I also bought a Park multi-tool that I carry with my Spot.