At the moment an approver can make adjustments to the dynamic content rulesets (Content and Rules) during the approval process. As far as I can tell these changes can't be tracked and aren't reflected back in the original template either. This means that mailings could go out with incorrect content and the only way to know it would be if you were on the recipient list. If this issue could be resolved, approval groups would be a more solid option as part of campaign management processes.