They are very, very good in my opinion. Directional, good wear properties, good grip wet/dry/cold. Did 20 laps of the 'Ring in a set this year and no scrubbing even on the shoulders. The 595SS are for the road and the RSs for the track; I'd have the RSs over the R888s any day.
Phil
And that's what you've got to remember when comparing them...they are not as grippy as a trackday special like the R-S2s. However, they will take a beating on track and not fall apart like a T1-R.The ones i've been offered are SS for road use.