Hi Guys,
From my own experience, stick with low roll center on a low grip track, the high roll setup seem to me is only advantageous in high grip conditions.
As for ride height, it does have an impact on how your car handles. I usually setup my car (414M2) with the nose slightly lower than the rear. This gives me slightly more steering and also quicker weight transfer from rear to the front under braking. However, this is just my preference on how I like the car to handle. Most racers either have the nose pointing down slightly or level front to rear...I rarely see racers with higher front ride height than the rear.
Steve Wang
Speed Tech R/C
www.speedtechrc.com