I have a 4-year old wheelset build with R36 model. It has a mileage of about 9000 km (ridden only on races and weekend club rides, mostly in dry conditions). After first summer season I noticed that the freehub got chewed in by the sprockets already but this is typical for an aluminium body. For example, mavic's freehubs are of steel. I have an old Ksyrium equipe set with about 15-20k km of mileage with no chew ins, only slight, surface corrosion tarnish. The rattle is pleasingly loud thanks to the three-pawl ratchet but there is absolutely no seal between the freehub and the hub flange so any bit of wet riding and you have to disassemble it, clean and lubricate ( for this I am using shimano's mineral brake fluid). Thankfully the disassemly is easy. As for the rolling, it's smooth, the bearings seems to be of good quality. However after first season I noticed a bit of rolling resistance in the front hub and discovered that it's the dust caps that I think got a bit grinded off on circumference making the contact surface with the flanges not smooth. Applying a little bit of grease dos not help it but I can live with that.