I'm a roleplayer myself, so I would love a server with an actual 'RP' tag on it, it helps to keep fellow roleplayers together on the same server and keep the roleplay alive.

HOWEVER, it is important to keep in mind that Balmung consists of far more than just roleplayers.

In my humble opinion, the best approach would be to select two low population servers and open up temporary free transfers to them. One could be labelled with the 'Roleplay Server' tag (Mateus would be my choice. =P ) and another could be selected for non-roleplayers who have no interest in roleplaying. It would certainly aid with the population/server stability issues, while also giving players who wish to leave a choice, in addition to supporting the lower population servers. Because let's be honest, the poor server hamsters that power Balmung are probably going to die on launch day of Stormblood, if Square doesn't take additional steps.