The way I see things, a good set of permissions would be:
1. Admin, can do anything.
2. Global Moderator, can do anything a moderator can do, in every forum, kind of like a castrated admin.
3. Moderator, can move/edit/delete topics in their forums.
4. User, Can post
And I'd also like to chime, that I like the current way that moderators are able to do nothing in the control panel but approve posts in their forums, but I don't like that they can ban users from the board.
Well dealing with a large site that is also taking in money transactions your idea is close, but not good enough for security. Small to Medium maybe, but a large site with thousands of posts a day and dealing with monetary transactions you have to have more than one Admin and he/she will need to be able to adjust certain things on the fly, but there are still things that you probably don't want "those" Admins to have rights to either.
The DB Tools is one. I think only a Super Admin or what ever you want to call it should have access to those tools.
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