I have the Dinan monoballs in front and had them on my last e90. In normal driving they aren't noticed. Ride is same, no difference in noise. Every now and then I get what seems like a loose feeling in the steering in low speed (parking lot) maneuvers when driving over irregularities in the pavement. I haven't tracked with the monoballs, yet, but I expect better steering response while under braking.
Another advantage is the elimination of the dreaded 80mph shake from the front end. My first car didn't have any problem with shake, but the second car had it. My 18 inch RACs made it worse with the necessary spacers. The monoballs eliminated it.
I'd love to have solid rear subframe mounts. I hear the new M5 has the subframe solidly mounted. I guess there is hope for M GmbH.
Dinan compliment of stuff plus PF rotors and RG63s. Enough for now.
Why, yes. I am an abrasive bastard.