The Korg PA300 first of all does not have Stereo line outputs which is a real bummer! Next, the Korg cannot be loaded with any new samples but the Yamaha has 32MB of sample memory to load in new packages which Yamaha sells and now there is finally a software application which allows you to combine the samples and styles from several different packages to make up ones that you want to keep in the keyboard. The PA300 can only have 1 pedal the Yamaha 2.
The Yamaha has an Aux input the Korg has none.
The Yamaha has arpeggios and controllers and the Korg does not
The Korg cannot record Audio wav files and the Yamaha can

The negative of the Casio WK keyboards for me is the styles and all the orchestral sounds. Casio could do a much better job of drum samples, guitars, brass, woodwinds, etc. I'm sure, but they haven't. Even in the demos of their new products from NAMM with the 5.2" color touchscreen, I never heard any guitar, brass or woodwind sounds played. Always it was Piano, piano and strings or organs. I'll have to wait to see the new products when they start arriving. I also think the Casio interface on the WK7600 is a bear to work with.