I just made a comment in another thread about this - I used to use a Roland EM-2000 arranger coupled with an 88-note weighted-action Kurzweil PC88mx because I couldn't stand the EM-2000's 61-note keyboard. And it sorta worked but it wasn't very ergonomic to get to the arranger functions of the EM while playing the PC88. Plus it was a pain to cart and setup all those boards and cords. I went to a single 76-note Yamaha 9000 Pro and have been very content with it. It's much easier to have everything at hand in an all in one unit then to try to work with separate units on stage.