Yeah, back in the 80s (when I first started the dueling deal), we had actual acoustic grand shells that WE gutted, and emptied. The concept was new, and the crowds were bigger, louder, drunker ... they often came up and sat ON the piano, so, we needed that level of strength. As the years advanced, and the crowds diminished, we needed to make the rigs more portable, and we gave up a little of that strength, in favor of reduced real estate on stage (and in the vehicles)
These little shells give a more polished look to the act, even though we know we're not fooling anyone into thinking they are real pianos. This type of act is request driven, tipping motivated, and full of farce and whimsy. Oh yeah ... and we play and sing songs too.