I can't remember if I've ever posted this before, but user accounts created on this site also work within FFXI @ xenoveritas.org. However, due to a configuration error, users created from this site would have no privileges to access the other site, and vice-versa.
I have now corrected this. All user accounts created from either site should work on both sites. You'll (currently) still need to log in to each part of the site individually, but your user account should now work properly on both sites.