Years ago when I was demonstrating and helping sell arrangers, when the technology was fairly new, the guy who owned the store told me to make it look simple. He said many customers can't relate when you play everything you know and do it so fast that they can't see themselves ever doing that.
I would play simple melodies with different voices and styles, and it worked like a charm.
Seems a lot of the demonstrators want to show how well and/or fast they can play.
As DNJ says, "Just sayin'".