I still dont get how we got from SK1 and Nord to Roland BK-9, they are totally different instruments..
A and B are performance keyboards
C is an arranger..(which is missing multipads and VH)

I will say it again, if you want a performance keyboard, stagepiano, workstation with Arranger functionallity, there is 2 options
i) a Ketron Module (or even a BK7) ii) V-arranger.

The BK9, just doesnt have the direct access the Nord and the SK1 (and the VR-9) have..

If you want a perfect all in one performance setup... How about the nord stage 3 (73 key organ version) with the SD40?... The SD40 is so small, you will not even notice the extra weight... and with the SD40 having VH and Microphone input, you will not need any extra VH or mixers.. just route the SD40 sound trough the Nord stage.. And the Nord stage compact is only 10 kg..