I usually do capo stuff as well, and when miced the same you get a really big fat sound. Quite a few of our songs are played with songs capoed like that live, and even more are that way on the CD.

On one track we actually have two acoustics stacked with different capos, making for four acoustics at once. Adding the electric guitar in and there's actually 5 tracks of me playing all at once! The things is, the acoustics end up sounding like a single guitar, just very big and fat, so live it doesn't sound so different when there's only one acoutic and an electric.

As for nashville tuning, I haven't messed with it yet, but I've heard it used to great effect (of course, being that I'm a Rush fan and Alex has used it many times over the years).