I use a capo on guitar and banjo, but never have on mandolin...closed position chords are very easy to pick up and use on the mandolin.

My wife's the fiddler and she retunes instead of using a capo.

We ran into Bruce Molsky at Clifftop last year and he showed us that he has outfitted his fiddle with a new type of geared tuning peg that looks like a friction peg, but isn't...he does so much retuning throughout a performance that he'd been looking for a solution like this for quite some time.

-Greg