I've added a footswitch in-line with the expression pedal which basically shorts the expression out. So I can set the pedal full for my solo sounds (with every effect setting tweeked using controllers) and just stomp on my switch to switch the sound with no latency at all. ( I could never get rid of the glitch switching amps, even when they were similar, but his way I can use completely different amps and switch instantly between them with no glitch, as all that is happening is a change in mix settings as both amps are always on.