I literally took delivery of the JamMan stereo today.
I've spent all day loading in the keyboard backing to the intro of Shine On You Crazy Diamond by Floyd. I recorded the parts on Garageband with its excellent choice of keyboards (the B3 Hammond is outstanding IMO) and then just simply recorded them onto seperate patches (each key onto a seperate patch), ie Gm intro on patch one, Dm on patch 2, Cm on Patch 3 and so on untill I have the whole keyboard sequence for the 5 minute intro ready to scroll through with my foot while Im doing duty on bass. 13 patches for that song
I also have a patch with the moog intro to Xanadu, and another patch with the air raid siren for War Pigs, you simply use the up/down funtion on the footswitch.
Im rehersing the Floyd tonight, I think I'll be tap dancing like Fred Astaire but should be a laugh, I'll let you know how I get on!
The main thing you need to think about is how you are going to change the patches ie the backing tracks, with you foot is the easiest option and for that you need the JamMan stereo, they're £112 at the moment at DV247