Then I pointed out how the Kronos gives me the choice of "Steinway," "Yamaha" and "Bosendorfer" concert grands and played a little on each one. It was amazing to see the facial reactions of several in the audience. One lady could be seen mouthing to the person beside her, "I don't hear any difference!," which summed up the reaction of many.

I'm amused at the number of hours we spend critiquing piano timbers. Most people in our audiences don't care. They just want to hear good music. I've known this to be true for decades, yet I still find myself stressing over which piano to use. It's true that not all digital pianos are created equal, but as long as it's a quality instrument most people won't notice the difference.
On a side note, I had a cool moment demo-ing the keyboard to some students a few months ago. The room also had a very good Yamaha upright. We A/B-ed individual notes on the upright and the Kronos. It was pretty scary how much they sounded alike. One of the kids looked at me said, "Wait, I'm confused." Made me laugh!