Hmm. I guess I don't mind a little hum from single coil guitars in a live performance. Always thought that was kinda part of the deal. Keeps the breaks between songs shorter too.
I worked the BET awards one year and Stevie Wonder was on.
His top keyboard was an old Hohner Clavinet. This pic is from that night:
He was located center stage (obviously) right behind where the set wall would come down after the performance. In that wall was a big purple neon sign of the BET logo. Keep in mind that a clavinet produces sound the same way an electric guitar does. There is a big pickup in it that runs the length of the instrument. A big SINGLE COIL pickup. When that wall came down the neon sign landed less than a foot away from the clavinet and a massive BWAAAAA of 60hz hum came out of every wedge on stage.
Oh well, that's live tv!