Permissions System has to be improved ASAP. In the current state the only thing it does is withstand users (esp. less advanced ones).
Let me screen how it might be.
In ACP there should be a tab (ie. Permission) with the table where:
<userName>, <currentGroup>, <setPermission as a docked table 3x3 and Read/Write/Roam>;
<UserName> | <Rank> | <Permissions as radio elements>
And below 3 buttons. Apply, Save, Cancel.
Easy, straightforward and well received.
PS. Its very high in priority grades as this do not allow newbies to customize their forum fully.