Hello,
i don't think it fit you're needs but:
I have 'struggled' with the same problem, what i have done:
My 'special members' on the website i have promoted to joomla group: Author.
With other words, you can add much funtions to the special members. Much components you can set on more functions for 'special'! I even have a gamecomponent greated, the Highscores are just being stored when a 'special member' play. I even have a 'now online module'. If a user is special member then they appear above of the list with a icon on the right
Go on and go on.
I hope that i give you an idea, maybe you can use it to get you're needs.
Much succes!!!
greetings , Lennox