I would rather have Josh's time spend on improving the editor, ironing out bugs, terrain and openGL4 than spending time on Networking. I agree with Red Oktober that people think it is easy to do networking once you have a proper library while most of them don't know how or even have finished a simple single player game. MMORPGs are, in my opinion, a massive undertaking that are not fit for a very small team, let alone a single person.
That said, the only time that I used networking for a Game, I used Enet in combination with SFML. I thought performance was pretty good but I have no idea how it would behave in 100+ players environment with complex server structures behind it.