TCB,

I've been meaning to respond but I've been very busy.

I'll give a quick run-down of my thoughts.

My first observation is, why worry about making the inner framework in your walls structural? This seems to me to be creating a lot of unnecessary joinery without a whole lot of benefit to the structure. My approach would be simply to make an inner curtain wall and let the outer wall do everything structurally.

With this approach, you could just build an outer wall system of any sort you wish. I'd use a 'Riegelbau' style frame, because I think it's well suited to this application, but I'm also biased. The inner wall then serves only as a means of containing the insulation and providing an attractive interior surface.

Off hand I don't see any great problems with your scheme, other than that it may result in more difficult joinery than you may wish to do. I am attracted to systems that simplify the joinery as much as possible, so judge my remarks in light of that not as abject criticism of your ideas.

Regarding double floors,

You are right that such a system could be more efficient from a materials standpoint. However, I would guess it's a lot more work to do and far less efficient from a labor standpoint. You will just have to choose which of these is more important in your situation.