Thanks to everyone for your help and advice. I have opted for the Nomad Mk2 for several reasons, size being one of them. It seems the 620L frame was destined for my leg length, so the decision was almost made for me. Now I am twiddling my thumbs, while I wait for it to be built and brought out to me in SE Asia. Needless to say I am really excited about setting off to wherever my two wheels take me. Maybe see you out there somewhere...
Thanks again
Tom
PS I have a few more questions, but I'll direct them to the relevant sections of the forum.