Before they even think of merging the servers, they need to balance the leves for each region.

Even in a low to medium population server, Camp Broken Water is still crowded like crazy. Just think of how much worse it would be to have the server population double overnight and have everyone try to do leves there.

The first thing they need to do before a server merge is adjust the mobs that spawn and the rewards for the Limsa and Grid leves so that they are on par with the best Broken Water leves. That way each camp will be nearly equally as good to gain SP.

Then, you can merge the servers.