Hence why they made the top tube out of it. :-"
Frame one, looks nice but how stiff is the fron end gonna be?
Frame two, nice but does the strut in the middle serve ANY purpose?
Frame three; hmm interesting its definitely a good concept but all those welds. :(
Frame 4, innovative and definitely a good idea to experiment
Frame 5, a redesigned mag???
I say that the seeatstays off the 3 and scale then down attach them to the front end of the 4 and see what you need as chainstays. Would probably be quite good.