I play on Balmung and I can confirm that it is the official "unofficial" RP server for FFXIV. You won't have any problems finding an RP FC. There are RPers in all the major cities and even some lesser ones. It adds to the environment and immersion of the game. I am not an RPer myself, but I enjoy seeing all the RP going on around me. Now just a warning there are some ERP fc's on Balmung, but they are not the majority. Only bad thing about Balmung is that it can be difficult to make a character on since the population is so high.