I'm with another website, Theres basically 2 community's there. The comunity i run has 150 members and we have no private sections besides admin only. The 2ND comunity has lots of private sections, the 2ND community's growth is very slow. We started out with the same numbers.
I understand what your saying there Dimitri, but i have never been a fan of private sections unless its for the admins. I think allowing more personally PM space is one thing to give to donating members, maybe there's other things as such...