Hi Corno Dolce,
I also saw this piano with a concave keyboard in one of the sites mentioned here. In theory, a concave keyboard is ergonomic as it would take advantage of the natural axis of the shoulders (meaning big intervals and leaps would need less reach and less leaning over to the right or left sides). It's good if people would consider making concave keyboards plus that concept of a dual manual. If I had the money, I probably would have commissioned building such an instrument.
If my memory serves me right, I think some manufacturers have tried building pianos with pedal keyboards albeit little commercial success. This makes me think that the piano might one day, in the right minds, become closer to becoming an organ in itself. :grin: