Interesting points.
The system can be reworked to take enemy elo into account more noticeably. Applying decay only when no AP are present (= inactive character) is an interesting thought and could work well. The reason for having account-bound elo instead of character-bound is also understandable. If we were to do this we should also remove the "Reset Elo" button on
https://fgunz.net/account/characters to somewhat prevent "smurfing" (player can still "smurf" using alt accounts). Though when you have 4 characters with the same elo we need to figure out how we'd like to display that at the ranking (
https://fgunz.net/ranking/individual and ingame) - probably only show your last used character or character with the highest playtime?