Caissus writes:
"Playing only unrated games after some time for non-paying members is the most used restricton on other chessservers"

But how, assuming it's factual, does this translate in net revenue production? What chess playing pawn is going to be compelled to buy a membership here because of the simple prospect of losing his rating status? Rather, it seems more likely he'd just go find another of the hundreds of free chess sites already on the internet.