Yo Sparky,
I was on a forum with the owner of this board (at that time he lived in Pa.) and got to speak with him soon after he had the bass unit installed. At that time, MasterSound offered a bass unit kit for installation into most arrangers. I was kind of hesitant to do the same thing as it took an inordinate amount of time to have it done and it was, I thought, very expensive. I instead bought the MasterSound MK4, 96 bass controller keyboard. The SD1 is a great board and the 37 lbs doesn't sound all that heavy, but the length of the board and the weight makes it awkward - for me - to handle - like the Korg PA1X. Plus, floppy, no HD or sequencer. With all that, I still would like to have it if the price is right.
Ciao,
Jerry