Today I tried to to connect my system-1m to Ableton using the USB interface. The interface is recognised by OSX as a core audio 12 in 12 out device so I know I have the special Roland driver installed correctly.
I have not found any documentation of the port mapping and so far I can only get a signal at the first four inputs. The first pair is the main outputs from the synth (including effects). Number 3 and 4 is the Gate and CV inputs.

What about the remaining 8 inputs? I've tried to monitor them in putting signals to all inputs but I can't detect any activity at all.

For the 12 outputs I've only figured out the first pair as the mains.