Wouldn't it make more sense to have two groups, one that gets to bypass moderation, and one that gets to perform moderation approval? I assume that people can be trusted to not be spammers sooner than they are trusted to perform moderation approvals. Or can the two functions not be separated?
I just mention this because I could understand if you don't trust someone to perform moderation approvals for you (especially if you have never had one-on-one communication with them), but I would hope that after 10 or so posts, it could be safely assumed that a person is not a spammer. There are only about 150 out of the 4410 registered users who have made 10 or more posts. Maybe they could be trusted to not be moderated? If not, there are only about 40 or so users with 20 or more posts, which makes them the top 1% of your posters. Surely you can trust the top 1% of your posters to not be spammers.
Also, just as a curiosity, what is the criterion to be approved? Just not be spam? Or is there additional stuff like not a duplicate in same forum, not a duplicate in multiple forums, not a rant, etc. If so, might want to post what that criterion is for your moderators for reference.
Mantis Version: 1.1.2
Disclaimer: Answers are based on the Mantis version above and may be inaccurate for newer/older versions which may have different configuration options and/or functionality.