Diki,
you make some interesting points
i THOUGHT this was a software thing,
and just as you can split the arranger, LH, RH,
i would think you can split the zone for aftertouch , on arrangers at least.
didn't know it was hardware, ribbon related, etc..
so it's ALL or nothing from what you say
but will still try it on my G-70

so i guess things can't always be as WE want them
thanks for clearing things up