I'm not a real good judge of organ sounds, but after owning the 500, 550, 740 and 2000 the sounds coming from the 2000 are far superior. If I were in your shoes, I would head to the nearest music store and sit down at the keyboard and try them out. If it sounds good to you, buy the keyboard. If it doesn't sound good to you, keep shoping until you find something that sounds better. You surely wouldn't buy a car before taking a test drive--it's the same deal with keyboards.

Good Luck,

Gary