I think how much you invest in a capo also depends on your playing needs. If I'm doing an open mic set and want to do one or two songs capoed, I don't want to struggle putting it on and taking it off. I want a nice, easy, quick one. I could transpose the songs but sometimes that does put it in a key that for me is just not user friendly. I don't mind a bit of a challenge but really sometimes a capo just makes sense. Even very good guitarists use them. Also, I play frequently with others who are capoed and I just can't transpose in my head, efficiently enough.
As to the length of the capo, it's obviously an important issue. I don't know of a regular uke capo that will work for a baritone. My small uke capo would handle maybe the first or second fret but after that it won't catch the E string. I think you really need a guitar capo, as it's not uncommon to want to capo on the 3,4, or even occasionally 5th fret. The trick tho is to also get one that's not too long either, as it can get in the way. I still frequently play first position chords, so this is an issue for me (on say a B7). The neatest, most smooth, low profile capo with just the right length, is important in this situation. Sure you can struggle on through with just any capo, but as I said in the beginning, if YOUR playing situations call for a capo with some frequency, get a capo your gonna be happy with. Be sure to look at the G7th performance capo 2. It's a little pricey, but really it's a small indulgence if you capo frequently.