Apparently they will never answer. Best I can tell the roll center of the car is the axis that your car body rolls on and is based on suspension geometry and where several angles meet up in the middle of the car. You want this point to be as close as possible to the center of gravity of the car. Lowering the car lowers your roll center too. This causes you to compensate more for body role with stiffer springs and things like that than you should have to. If this actually does make the roll center higher then it would be beneficial. I'm not an expert though. GKTECH should be giving me a discount for doing their work here.
Moves the subframe higher up closer to the chassis so your entire suspension geometry is higher up so you have a lower center of gravity and essentially can lower your car more without affecting suspension geometry as much.
