The action feels almost identical(It should because it is a Yamaha keyboard). This is the graded hammer action as used in the PA80. Korg uses a Yamaha keyboard for the action on the SP500 (made in Japan, not Italy). Korg doesn not manufacture their own keyboard actions. If made in Italy, they use Fatar and in Japan they use Yamaha.
The sounds are great! There are many pianos to choose from.
George Kaye
Kaye's Music Scene
Reseda, California