I have a PSR 1500 and a Pa500. I agree with you, the sounds in the Korg are far better than the Yamaha�s at this range of keyboards and most of the sounds are usable. Yamaha has, on the other hand, a much easier operating system and practical way of storing styles and songs. With the SM card and Usb stick all the styles are at the tip of your fingers almost instantly. I even prefer the buttons rather than the touch screen which I can�t use well for fast changes. I have never owned a Roland so I can�t compare it yet. And yes, the internal sound system and speakers are better in the Yamaha. I use all my keyboards in tandem so I don�t miss anyone.
Victor.