No I'm sorry, but that's not what I've been looking for.
The problem with your suggestion is that it can be done per-member only, you cannot assign a whole usergroup as a group moderator.
I know it might be hard to understand, but think of larger scale forums where you don't just have one group of admins, but instead you wanna have a group of "real" admins with all rights on every board (which is an extremely small group of people) and another group e.g. "Administration Team" for the forum which should have most of the admin's rights like "Assign primary membergroups" and "Assign additional membergroups" but they should not be able to have unlimited access to the forum, it's maintenance tasks etc.
This you can only achieve when the permissions are split as suggested.
Best regards - Mike