Hi:
Actually, I saw Pat Metheny last evening and during one song, he played a very unusual guitar which is (from his website) a 42-string pikasso guitar built by Linda Manzer. It has two necks - one appears to be a 12 string and the other a 6 string (although it may be a baritone) and there are two separate configurations with x strings (couldn't count them accurately).
He kept up a variety of background "patterns" going on the two string configs and played the two necks. The similarity of looping with a standard looping device and what he was doing really struck me. I'd like to see him use something like an Gibson Echoplex live. It would probably be amazing. He certainly was last evening. That guy can cook!
Regards, Paul