The topic is hot, and it's not easy take a decision. I personally think that an omogeneous world is better than a flat and boring one, I'm in favour of mixed servers where people from all over the world can play together. I'm aware of the huge lag issues that afflict the game NOW, and what I hope at this point is that in the future even on a japanese Data Center lag problems will be lessened. (Check Ifrit's Eruption video to have an idea about)

I'll try to create a PG on a far Data Server to check if it's playable or not... But actually I'm not convinced about what to do when time will come...