Hi...I have recently bought this controller keyboard and the aftertouch is very hard to trigger, you really need to push down hard on it to get any response.
Pushing down on the end of the key means you are close to snapping the keys off before you get a response, pushing down in the middle of the key brings the easiest ( but still hard ) response.
I used to own a Fantom X and then a V-Synth GT and they too had pretty hard to trigger aftertouch responses but not as bad as the A-800 Pro.
Is this a typical trait of Roland aftertouch or have I just been unlucky?