I have both the SP500 and the P80 at my store. Both have good action, both are light weight(although the Yamaha is a few lbs. lighter) and the piano sounds are very good in both. So......the choice is....do you want an arranger keyboard and a Piano (korg) or do you just want a piano with nice keyboard sounds and split and layer options (no performance memories however on the Yamaha). Also, the P80 sells for around $899.00 and the Korg is around $1499.00. I don't remember if the Korg has a to host port but I will check when I go to my store this morning.
George Kaye
Kaye's Music Scene
Reseda, California
818-881-5566