If it helps you at all in relation to dampers and springs.. It is extremely common in the racing world to have an over sprung car (too stiff of a spring for too light of a damper) due to the inflexibility of a lot of the rules. This is basically how the H&R's feel on my sport line and it won't really cause any problems for your dampers but they will not last as long. If you expected 60k miles, you can now expect 40k but I would have tossed them by 20k even without mods.
KW v1's are in the $1600 area and while I can't speak for this exact setup because I don't think anybody has enough miles on a F30 yet, I have had KW v3's on another car and they required rebuilds fairly often (like 3-5k miles) and it was just short of $500 each time.