Hi Purus,
every Oxwall page is different, some have very active members, some less active members etc. The point system is hard to adapt, if not made exactly adapted to the site, then one can have all members as experts etc....
I suggest you let the admin define PERCENTAGES.
That means for exemple:
5% of most active members = "expersts"
10% least active members = "neebies"
etc.
of course a definition of what is valued more (image upload, blog posts etc.) would still be necessary. But the percentage key will assure that one cannot have 90% experts or 70% newbies etc.