Base density definitely determines how durable the base is. A 2k weight sintered base is not going to be nearly as durable as a 7500 weight durasurf base. This is just math. Lib uses a 9k weight base, atomic 7k, K2 uses 4500, I have no idea what Salomon uses on their rocker 2 but I would guess it is sub 4k, the Suspect used 2k and that's all the info I can find.
When I can actively run rocks and stumps over with my lib-techs (because they are 3 years old and I don't really care if I do manage to break them, although thus far they seem unbreakable) and have them come away pristine. Then on the other hand, I baby my rocker 2's taking only well covered terrain and avoiding any low coverage areas only to find mystery giant scratches at the end of the day I think it's safe to say this is a durability issue.
Also with my K2's I would usually know if I did some damage, I would feel the rocks I hit during the day and make a mental note that oh, that probably did some harm. I never saw or felt myself hit any rocks on the Salomon's yet still came away with visible damage.
As far as maintenance goes I'm OCD about waxing everything once, sometimes twice a week (as well as deburring and removing rust). If anything the Lib's haven't gotten waxed as much this season.
There are other factors at play here that we simply don't have the info for, such as the base manufacturer, if they used any additives, etc. I understand anecdotal evidence is not a great thing to rely on, but until manufacturers are more transparent with their ski constructions it's all we have to go on.