The "Three Improvisations on Modified Banjo" CD or "Four Improvisations On Modified Banjo and Guitar" 2xLP (same thing with one bonus side of modified guitar goodness) are similar, but emphasize a more fluid and inhumanly skilled raga influence. A bit of Asian influence on one piece as well. Not quite as "jagged" as the guitar stuff, but similar in certain ways, especially the influence of North Indian stylistic leanings. The banjo stuff is still super-extended timewise, but a bit easier listen to people not normally into the "way-out shit." It's still pretty way-out though.
The debut LP on Mutant Music has one side of fluid modified guitar and one side of jagged angular improv on that same instrument.
He also has a new cassette out on Freedom From called "Maccaferri," which is all recorded on a Maccaferri plastic guitar, bookended by pieces from an automatic instrument he has made with many many music boxes, all of which have been altered somehow. The guitar pieces on the tape are severe deconstructions of Monk's "Bemsha Swing."
I would start from the banjo one though; that one is really amazing and shows Metzger at the peak of his powers, plus it sounds incredible. Recorded at Sacred Heart in Duluth, with all-natural reverb.
EDIT:
Sound samples from the new cassette and upcoming banjo LP on Roaratorio here:
http://paulmetzger.net/