I too would take this XIIIUM rumor with grain of salt. If it were true, it could be re-balanced XIII or XIII with content that had to be cut years ago.
Music on the other hand... What I've heard so far, new Esaka is kinda meh, I liked this saxophone theme, although it sounded like a opening to a crime TV-series. What I've heard from streams, I guess K' team's theme sounds kinda nice. I still hope I can buy soundtrack someday.