I'm definitely more prone to use a 4 cam unit when I have the option, but there are places that TCUs fit where my smaller C4s won't. As far as the U stem goes too, I don't have any issues in placement as long as I can turn it in the direction of potential pull (which usually works out unless the crack is uber tight). Walking could be an issue with these, but as long as your slings are properly extended and you don't take multiple falls on the same piece it shouldn't be a problem. Anyway, Sizes 1-3 are a standard part of my rack, they're super light as far as cams go, and I'm glad to have them. Unless it's a fatter crack climb, usually at least one of those 3 gets placed.