A Sins MMO...interesting idea, but I wonder how computers would deal with having 100,000 ships at a time. It might require a radical reprogramming of the game so that it were server based.
I would prefer it be server based, users are too unreliable to be responsible for hosting.
I dont like the MMO idea though, personally I prefer starting each game new, thats what this game is all about really, doing things differently each time.