My car has Bilstein M1 dampers (which feel very, errm, "well damped"...) and originally had the green springs (250lb front, 215lb rear). Rock hard, good for the nice smooth track, but difficult to hang on when navigating a bumpy B road.
I can't afford the oh-so-very-shiny-my-precious Nitrons, but I do fancy something with adjustable damping...
Springs are currently 150lb front (std Caterham issue which I had on the shelf, but would have preferred to try 175lb)) and IIRC 120lb linear rear. Red (widetrack) bar on the front, Freestyle adjustable rear.
Can't comment about the performance as I haven't had it on the road yet!
Anybody care to post their experiences of Protech?