Brian, I bought a Martin Sigma 12 string for one recording in the early 80's. Only used it the one time out, because I use an Ovation double-neck with a 6 and a 12 when I need acoustic. Last year, when bored, I put in a pick-up and use a Sans Amp pre-amp around home.
You're right: for the money, they are pretty neat guitars.
Of course, my problem is I love ALL guitars!
Russ