I've seen this idea floating around however it's really good to see the groups broken down like this.
I'd go for labels like "superhero" and "legend" instead of "mod" or "supermod"
NB - IF (and I'm not certain it's desirable) Steemit goes down the route of moderators (in the true sense), I don't think this should be based on SP only. It should be reputation based and maybe voted on (a la Witnesses). People being able to 'buy' moderation privileges is probably not a good idea.
Is this because "mod" has a stigma attached to it? That's the impression I'm getting. Thanks for the label suggestions!
Would users aspire to "superhero" and "legend" status as much as "mod"?
And there will be no mods (reddit style) besides the current Steem Power system where everyone is a mod to the extent of their vesting.