Small update
Finally installed the Bimmerworld trailing arm and camber arm bushings.
Swapped sprigs to Swift Spring 10kgf and 16kgf (from 9 and 14), re-aligned and rebalanced the car.
Quite a bit better feedback from the rear end along with stability. Now working on resetting the MCS shock settings to accommodate the spring rate changes.
The install was surprisingly easy as the old stuff comes out fairly smoothly as long as you can apply the pressure to the right parts of the bushing. Installing the new stuff was easy as well as everything was made to the right tolerances.