I can just say the same as York. I'm still not sure if I want to buy this game because I'm not always at home while playing. I mean you can still use online authentification if players want to play on public servers but on the self hosted server?
Minecraft did it right with their offline mode.
To be honest, if someone wants to pirate the game, they do it, no matter how much you protect the game. Pirates have more features than a supporter of the game.