I haven't been very involved in v5, so I'm going to start contributing a bit here.
Here's the basic formula:
Rating = (Seniority * Rep) - Wounds
Trial Member: ONLY member group allowed for anyone who has under 5 or 10 seniority points.
Rating < 0: Restricted. Uh oh.
Rating >= 10: Member
Rating >= 100: Regular: Must have at least 75 seniority points.
Rating >= 400: Elite: Must have at least 200 seniority points.
^Of course, we can always change the values and add new groups, just some theorycrafting.
Seniority - Increases by one for each day the member logs on to the site. Maybe there can be a button or something to push every day, or just have it not increase if they haven't posted within a certain amount of time since the last increment (24, 48 hours). I'm biased towards seniority, sorry.
I really don't like post count or posts per day to go towards the formula, so this is the closest thing to it.
Reputation - This one gets a little more involved. Reputation starts out at 100.0%. A member's level determines to what degree they can affect it. Each member can set a value for any other member
ONCE, but they are able to change their value at any time.
Trial Member: Cannot affect reputations.
Member: Can affect reputation on a -.2 to +.3% scale.
Regular: Can affect reputation on a -.3 to +.5% scale.
Elite: Can affect reputation on a -.5 to +.7% scale.
Staff (?): Can affect reputation on a -2 to +3% scale.
Global Mod (Higher Staff?): Can affect reputation on a -4 to +5% scale.
Admin: Can affect reputation however they want.
And, of course, the Staff and above must factor in that they must use reputation fairly... they have the next factor for punishment.
Wounds - Admin fun time. When someone is warned/fined/disliked by admins or whatever, we set this to some number. It is subtracted from the whole thing at the end. The wound value is "healed" by 3 per day... or some other value. Maybe a percentage, or the mod/admin can set a value for how much to heal it.
And, that's it. Expect a few edits.