It is, in my opinion, a major no-no to rename a series. For good or ill, the names you begin with are generally the ones you're stuck with for all time. Names become the very heart and soul of a series, anything else - even if more clever - just won't be the same. If renaming things were really a kosher thing to do, I would have long ago pushed for a renaming of Chrono Trigger Unglued (and a few other things).