Okay, a new version is
now available.
This version reworks things so it has a defined constant that determines which of the two variations to use on the user's profile and in topics:
1) the special rank (e.g. the Administrator rank) should be shown in the same place as the normal posting rank (so any theme that doesn't add the 'extra' rank still shows the Admin badge) and so the posting rank becomes the extra rank on forum themes that add it
2) the posting rank should remain as normal and any special rank (e.g. the Administrator rank) should be shown in the 'extra rank' location, meaning that any forum themes that don't include the extra rank will only show posting ranks.
Even after these changes the memberlist should still just show the special rank, if one applies.