Jason,
I don't have any experience with the front weights, just rear.
When I was clearing the larger trees there were times that I probably could have used even more weight in the rear for the heavier lifting, digging, and stability in carrying- the rear ballast, per the dealer, is around 1000#'s(Rimgaurd).
In clearing there were some pretty wet areas that I had to drive through while carry the heavy trees or dirt. It actually surprised me when I looked at where I drove through without any hesitation-I didn't realize I was cutting down that far and leaving such deep, water filled ruts. I stopped going through the wet areas after that but it did not seem that the 6500#'s of machine hurt the traction any. I also have R1's and they seemed to help greatly with the traction.
Going out to do some more tonight-can't wait!!
Jeff...MI.