A few comments from a music store owner with both models in my store:
The Korg PA1X when it first came out gave me some problems. I found that there was such a small area where your touch would actually make contact and trigger the change. This was especially noticable when selecting single touch settings. Even though there is a lot of free space around the name of the sound, you had to hit just in the center of the name. Then, Korg came out with new software which made the area larger around a word or icon so you didn't have to hit in such a specific spot. Now, I have no problems at all with the touchscreen.
Rolands G70 offers the click when you touch the screen and I find this very usefull because I can an audible sound telling me my touch triggered something. I've had no problems selecting things from the G70 at all. When I sold the VA products, I often found myself touching several times before making a selection but this has never happened with the G70.
George Kaye
Kaye's Music Scene
Reseda, California