Had this setup on my '11 zcp and liked it a lot especially in the sport/firm setting on track. The revised programming for the firm setting works really well imo. Normal setting allowed for too much body motion imo on track and was good for normal street use. I used comfort sparingly (mainly on bad pavement) as it was too much body motion for my tastes.
As far as lowering, the usual spring combo you get will go as low as you want in the rear and not a lot more in the front. You can spec shorter front springs and again, go as low as you want. Best thing to do is call GC and talk to Jay about any questions. He won't steer you wrong....
Bottom line is this is the best bang for the buck suspension for the e90/92 M3 IMO.