djx won't be good if you´re not making techno/dance/trance/hiphop and so on...i´m not a big yamaha fan but i really think some keyboard from their psr-serie would be much better than casio...i don't know how it is these days but year ago or so,casios weren't very good...why don´t you just test ctk631 and if you like it,then just buy it...=)