I think the whole point is, you've got to pick up an instrument and hear the possibilities. If you're happy with 5 stringed banjos and 6 stringed guitars and can't figure a way to make the sound and feel of something different work for you, it's probably not your instrument.

It sounds to me like the 6 stringed banjo is to a guitar as a harpsichord is to a piano. It's a plinkier sound. Some folks will like it and some won't. I happen to really like Harvey's 'Pieces of Eight' and don't think it would sound nearly as good with the sustain on a guitar. Personal opinion - and I ain't gonna buy one because Harvey's weighs a ton. (And is to a regular banjo as a hand grenade is to a BB gun.)