All in all, I love the concept, and it is actually following a design parameter that several Timberwrights (myself included) are starting to explore and/or employ in their designs. Much of it is nothing new and more a "dusting off" of some older vernacular methods from around the globe.

I love "Double Roofs" and can not expand enough on how functional and aesthetically pleasing they are. That was a wonderful choice...

As for insulation, I no longer use "blow ins" as they are to plagued with long term issues and/or do not function as claimed. I prefer and use either natural insulative materials, mass systems like log, plank, stone, cobb, light cobb, adobe, etc. For a "modern insulation" (yet over 150 years in use with excellent results) I employ mineral wool batt and board.

Your design is very much like a "Wall Truss" however I would say more than half of these contemporary wall systems seldom are "hung walls" (though this works well if designed well) and actually rest on foundation of some form...

Wall trusses and your modified timber form of them both lend themselves well to "cold roof" and "rainscreen" modalities as well...

I look forward to watching you develop your concepts.