Im probably the only person on the forum that has used KW CS and JRZ RS1, both with 500/800 spring rates. I have used both on my daily drive, which is about 50-60km, which includes downtown roads and freeway. I have tracked both set ups.
I can say with out a doubt, the JRZs do everything better and are well worth the extra cost, especially for your daily commute, the ride quality is far superior. The KWs were very good out on track actually, I had no issues with them for track use.
One extra note, having great vendor support is also very important. James@Bimmerworld has always responded to my questions quickly and really helped me dial in my set up to where I am extremely happy with it. My local shop that does the work on my car is also very competent which is another must IMO.
2008 AW/FR E90 M3-SOLD
2013 991 C4S-SOLD