I run H&R Race on my M3, and I've ridden many times in Rob's 325 (on UB) which has H&R Sport.
Both are very stiff, and it really comes down to your preference. If you put Race on your car, you lose most of the luxury appeal of the car because you feel EVERY bump on the road. No constant vibrations with either (straight roads are smooth); it's not like a truck, however you sure as hell better dodge potholes or it hurts, lol. Sport is a bit softer, but still very stiff, and while you still feel every inperfection in the road, it's toned down a bit.
I love my H&R Race, and the occasional bumping doesn't bother me really, but the girls dislike it a bit, haha, but it's okay because I make up for it by downshifting and making them smile again.
I'm also running Bilsteins with the springs on my m3. I'm not positive what shocks Rob is running, but I'm pretty sure they're Bilsteins also.
Hope that helps.