Frank,
I would say that it's a LOT more than the SD1, because in the SD1 you can save only a registration at a time on the hard disk and so, to have more than one registration to play "Wonderful tonight", you should save them as "Wonder1" "Wonder2", etc; then, when you need to call them while you are playing, you should press a lot of buttons to access the hard disk, scroll through the registrations to call the right one...and you have to play or sing at the same time! With the Tyros you have eight registrations laid out before you: just press one button and you are set!
That's one big advantage of Yamaha over Ketron: ease of use, with a friendly and logic interface.