DavidL- I saw a picture of you at the worlds, I was wondering what you were doing since I didnt see your name on the entry list.

On roll centers... In 4wd i am pretty sure that when you lower the roll center it takes away traction, because it keeps the chassis from rolling and transfering the weight in the corner, so the chassis stays flat. I would assume the same is true for 2wd (unlike castor...).