have you had a good look at the high performance, packable/folding all terrain bikes out there? examples are: Airnimal Rhino, Pacific Reach, Moulton TSR, Bike friday Llama, Airnimal Joey, Swissbike, Tikit, Birdy... the list goes on and is growing. Each bike is best suited for different things, and I appreciate wanting to make a "do it all bike", which is pretty much what I was striving for with my Tikit, just make sure you are not re-iventing the wheel!
....or is that precicely what you mean to do?