The 6 degree beam definately does a lot for the handling. It cured a lot of understeer on my 4x4. And science also says it's a good mod. On a standard beam there is a lot change in the toe and camber over the suspension travel. The toe change is what is causing the understeer.
I don't think it's a problem that the rear roll centre is lower with a 6 degree beam.


Ford had already thought of a beam with a smaller sweep angle when they made the RS500. It had special brackets mounted on the subframe to homologate the moved inner pivots for racing. The race version of the RS500 had sweep angle of 8 to 9 degrees, which was the maximum they could achieve within the rules.


I also look forward to having the new parts fitted and seeing how it will handle then. The new TCAs are still in the box, it's way to cold to fit them now and the car is still off the road anyway until the weather is getting better.