When you hit a bump or expansion joint you're compressing the damper whereas if you run over a dip or pothole the damper is extending - difference between compression and rebound damping response. Adjusting "clicks" on the damper won't significantly improve the compression response because the RS1 "primary" damping adjustment is rebound (compression changes as well but to a much smaller degree); however, the damper has a bleed valve to help absorb "compression" bumps - it's the bleed valve that's keeping you from "bracing yourself" when you think it's going to be a hard impact (i.e., good example is hitting a bump mid-corner and the damper absorbs it so you maintain grip instead of skidding across the track!).
I'm surprised you find the ride with 425/700 rates set at 4 "clicks" from soft to be similar to EDC on Comfort, and 6 "clicks" similar to Sport. On my M3 I'm running RS1's with 500/800 rates with 10 "clicks" F and 8 "clicks" R yet I find the ride to be very street friendly. On my wife's car we're running 400/672 rates with 8 "clicks" F and 7 "clicks" R and we both find it to be extremely street friendly - both in rebound and compression. Personally, I find the RS1's to have a huge range of adjustment and to be a great dual-purpose damper (much better than the Ohlins DFV dampers I'm running on my Mini). However, the problem with suspension setups is everyone has a different tolerance!
I wonder if adjusting the internal reservoir N2 pressures would improve your ride characteristics?