I have them and have done a few days with the zcp and a few with the sleeve kit springs.
The car is lower and stiffer so I like the way it feels. Transitions are not as sloppy either but be careful with your ride height. Too low and the car will bottom out on the bump stops.
Current: SBM X5d, SPEC E46 racecar, Black FJ Cruiser, 1970 240Z
Former: '11 MCB E90 M3, 2011 Lotus Exige, 2003 350Z, 2002 WRX, 1996 Supra turbo, 1984 320i, 1987 E28 M5