I have mixed feelings about multitools in general. I own a Leatherman PST, Leatherman Charge TTI and Leatherman PS4. The first two don't see much use at all and the last one... well... it comes with me in my sky touring outings just in case a binding needs adjustment or a multifuel stove requires tinkering.
Other than that, my feeling is that if you need to use a multitool in a rgular basis, you are doing it wrong and should be carring the real full size tools instead. Pliers in the most recent models are not that uncomfortable to use, but nowhere near a pair of decent pliers. The screwdrivers are only suitable for shallow placements, as they don't have a long shaft to reach recessed heads and are difficult to turn as the handles are not symetrical. The knives... meh... we all know they do cut, but any dedicated folding knife is going to be more comfortable...
So... if you don't plan on using it and carry it just in case... ok, perfect. Either on you or (better) in the backpack if it is full size. A PS4 or similar weights very little and can go in the keychain if you want.
Mikel