Didn't Les Claypool used an (modified) MP-2?
I don't know what Les used later on, but I can confirm he used an MP-1 during the Frizzle Fry tour. He and Larry LerLonde used MC-1 footswitches at the time, I don't thing the MPC was even out yet, let alone the MP-2.
Fun Fact: I was using an old Boss ME-5 (the first multi effect from Boss) through two half stacks when my band opened for Primus on that Frizzle Fry tour. They are the reason I started using ADA gear in the first place. Seriously. I wondered what kind of sorcery was behind this simple footswitch and wire apparatus they had onstage and just had to investigate. Been down that rabbit hole ever since.
Cool thing about playing with them was that we got to meet/hang out with the fellas, great bunch of guys. Very humble and fun, and yes...funny. Funny looking, funny sounding, funny personalities - we seemed to get along well, our band was full of geeky guys like them. nerdy musicians rule \m/