Great to hear you're still loving them after a few years. I'm about to buy a used X3, and it's freakin' impossible to find one with the DDC package on it. Coming off a 535 wagon, I am looking for lower wheel gap, and hopefully an improvement in handling as well.
Funny how this guy here hated his H&R Sport Springs:
http://x3.xbimmers.com/forums/showthread.php?t=829676
I wonder if it's because he doesn't have the Dynamic dampers that you do?
And not to state the obvious, but I thought you always are supposed to get new shocks too when getting new springs, as otherwise the shocks will get ruined over time from being compressed all the time. Are you able to get away with that because you have DDC? Or can you just do the springs on the non-DDC cars too, and be fine?
Otherwise, it's KW V2 coilovers it looks like for me. Have you come across any reviews on those?