I have four 45 ACP revolvers which obviously all take moon-clips. I think they are "the way" to carry spare ammunition and to reload these revolvers. Nothing is as handy or fast. Someone above asked if speed loaders would be just as good and faster. Simple answer: No and not even close! The trick to using them is, as advised above is to have the proper loading and unloading tools...and keep a good supply of full moons on hand. I have about 150 of them and keep an ammo can full of the loaded clips at all times. Going to the range with one of the 45 ACP wheel guns is actually easier than taking a semi automatic. No magazines to load either!
I also have two PC S&W L-frame 7-shots cut for moon-clips. They too load more easily and faster than the HKS speed loader. The problem with these is the clips for rimmed cartridges are much thinner than for the 45 ACP and thus they are more prone to bending. Still they make loading so much easier it's worth the hassle of occasionally replacing one.