Yeah, it doesn't really work like an "infinite delay layering" kind of thing. You program your autoriff device to play certain steps of a scale in relation to what note you're fretting, and then you turn your back toward the audience and fool them into thinking that you're Buckethead.
So far, the coolest thing I've found to do with the autoriff function on the GT-6 is to remove the cable from the guitar and just grab the connector portion of the cable. Sounds kinda industrial/bassy/keyboardyish. I think that touching the cable to my nutsuck with the autoriff turned on would be a cool live thing to do, but I'm a little scared...