Hi ... interesting topic ... like Gary, I also do a "demonstration" at some point during many gigs. I did a gig yesterday; it was at a place I hadn't played in ~6 months, and I could see plenty of "new" faces (as well as people I remembered). So, about halfway thru the gig, I told them a bit about the keyboard, played some quick lines on single sounds (piano, sax, clarinet, trumpet, organ, etc.) then quickly showed how I play/control a style (showing them that I use a foot-pedal to add drum fills), then showed them a quick song where I first showed that I had guitar in the left hand, piano layered with strings in the right, and a solo trumpet up on my 2nd little keyboard. I could tell some of them seemed fascinated with how it all works ... (esp.
based on the comments and questions after the gig).

I like the idea (can't remember who mentioned it) of playing an occasional piano-only piece; I do that, and sometimes play a classical medley that uses no styles (just piano, strings, an oboe, stuff like that) ... helps remind people that it's being done live etc.

-Jim