Premium accs is a very hot topic. Many ppl want it, but it also could ruing a game balance easily. But I opened this server not to get money. Premium acc concept is not completed yet (no fancy hats in C1, maybe with C2 will add them).
Most probably, there is won'be any exp/sp/drop/adena boosters in premium accs.
Maybe 2nd proff marks will be given as a bonus for donations. This shouldn't break balance, just saves some adult person 2-3 hours from well-known quest. And this is one-shot action (even with multi-boxes it has limits)