I have Moton Club Sport with Eibach springs - 500 front, 800 rear. This was chosen for me by Woodhouse (they installed the system). I haven't tracked the car yet.
I do have 2,300 miles on the car, and can compare it to the '03 SRT 10 that I previously owned. Recovery time in hard cornering is improved, so chicanes can be done faster. Wheel hop is much, much less. Pavement tracking is decreased.
As others noted, the improvement is pretty dramatic. I suspect the SRT engineering team would have preferred a Moton suspension on the new SRT coupe for all the magazine comparos. At last weeks SEMA show, they equipped the concept Copperhead Coupe with several Mopar goodies........and a Moton suspension.