Moderation is just a target for trolls. Meta-moderation-threads can generate huge angry threads of hate. Meta is death, but meta-moderation is evil slow death.

Highlighting comments from established contributors is a problem if some of them are dicks, or some of them occasionally make awful comments. You also have a problem with "vested contributors" - 'I broke the rules, but I've been here so long and do so much good that it's okay because you know that really I'm alright' whereas the newbie just gets banned.