Nice to see someone taking a RATIONAL look at backpacking stoves. The appeal of the downdraft gasifier appears to be more romantic than realistic. There's a paper, "Design Principles for Wood Burning Cook Stoves", which contains a lot of no-nonsense information for designing a cook stove. The PDF file can be had on-line. Just Google the title.
I've made a couple of stoves based on this paper (see my post: high efficiency wood burner & two cents worth on wood stoves) and near as I can tell, they appear to perform at least as well as the bush buddy (I say appear because bush buddy doesn't publish enough information to determine its efficiency) in still air, and are the hands down winners in a breeze. Oh, and it uses an aluminum outside shell and a stainless steel fire box. I would have tried TI but the stainless steel was what I had on-hand.