Wow...I'd have to give it some thought, but I'd be hard pressed to come up with a Priest set list that would legitimately work with only one guitar. Even if Ian Hill started playing with more distortion or used an 8-string bass, there'd still be no way to recreate the harmony guitar parts that are a HUGE part of Priest's arsenal. Really, the only way to do it would be to have a backing track live, which would be LAME.