That would mean giving global mods the Moderator Control panel access though, and I think that could pose as more of a security risk since it's best to have as few people with access to that as possible.
There are still plenty of things which smods can do, such as dealing with avatars/signatures/profile pictures, which in itself is a big job. We also have the power to do the manual cautions, check IP's, ban users etc.
We're still there to essentially help moderators out where needed, and act as a support for them should they need any advice on things. Quite a few of the moderators are new at the moment and so it's important that they have people on hand to ask etc.
I think having 6 "supermoderators" would be quite bad really, since everyone would just get on each others toes and most likely deal with the same stuff, wheras at least like this there are still divisions.
You need to gain trust and show you know what you're talking about to be a super moderator and I don't think it would be wise at all to give control panel access to people who have not long been in a department, and through them straight in to dealing with a whole bunch of things other than general post moderating. They already have more to learn and take on board now with post reports etc, and this in itself is a big enough change in my opinion which should do the forum some good, whilst ensuring the two roles are still different. We are essentially just "senior moderators" and we do our best to ensure the mods have someone to come to if they need help, ofcourse along with forum management.