It's one of those things I miss. I figured I wasn't using it enough, so I sold it to my brother and now I miss it.
I agree with Stringsinger about the octave string in the third course.
I have an old Yamaha that I keep strung in Nashville (high-strung) tuning to get that type of sound, but not as satisfying.
Spider John Koerner doubled his G string with an octave string for the Koerner, Ray & Glover LPs and a few years back, Roger McGuinn got Martin to make him a Spider John style guitar.