If you want to play it like the other keyboards (controlling styles with left hand and at the same time playing melody with right hand), buy PSDD1-DJX, because you can't play DJX-II this way!!! Also, if you want to connect it to computer and use it as a controller keyboard for recording notes into computer sequencer, you also havo to buy D1, because DJX II does not transmit notes through midi out. And D1 also have touch-sensitive keyboard, while DJX-II does not. But if you're going to play it more in a DJ fashion (like groove box, applying effects in real time, playing with pre-recorded phrases), buy DJX II, because it is more direct and easier to operate _in real time_. DJX II is a groove box with keyboard interface, and can't be played as a normal arranger keyboard, PSR-D1 is arranger keyboard (styles and everything) with techno oriented styles and sounds, but it includes also standard general midi sound set (DJX-II has only a few sounds from general midi, everything else is techno).