Pretty much covered as above, for me, since I do a lot of lead singing, it's putting the song in a key/context that works. EDIT: thinking about it, probably used a capo more in an acoustic trio I was in, to add a different bandwidth, chord set, sound, etc. The only add I would offer is the partial capo technique, for which a regular capo works fine. One example, put the capo at fret two, across all the strings except the low E. Now you got a version of a drop D style tuning, but no actually re-tuning required. I've used all kinds, but favor the Shubb. There is a technique with a Shubb (and probably others as well) where you place the contact rubber bar on top of the fret, and that does minimize any re-tuning, if done carefully. That does cramp the available space near the capo a little, but like anything else, just takes a little getting used to it.