Directly from the Manual:
"Rear Roll Center: The rear roll center greatly affects the handling of the car. By raising the center pivot point, your decrease the amount of chassis roll making the car steer more. This keeps the inside tires planted, resulting in a more aggressive chassis. Conversely, when you lower the rear center pivot point, the chassis is more affected by weight transfer and exhibits greater chassis roll. This weight transfer, or roll, takes weight off the inside front which takes steering response away from the car. The AR center pivot makes adjusting the rear roll center very easy."
I am in full agreement with the description above regarding the rear roll center adjustment. It doesn't matter where the rear roll center actually is, tuning the car by adjusting this pivot will have the affect described. It is easy to see that in this case, the roll center is lower than the center of gravity (CG) of the rear. If the rear roll center was higher than the CG of the rear of the car, the affects would be opposite. My experience with all the 1/12 cars I have owned and raced supports my comments as I have made these adjustments in the past and those changes follow the description in the manual. Comment number 76 above is sort of confusing to me.