I can't help you in which BF to buy but I wouldn't buy a bike based on a 6-8 week bike trip three years from now. I would buy the bike that will best suit your immediate needs and what you plan to do with it for the next 5-10 years (if you keep it that long). My question to you is what are you primarily going to use the bike for? Then buy it for that purpose. You can make any bike travel for a once in a lifetime trip, even Bromptons have been known to be used as touring bikes.
From what you have said so far, the Tikit seems like the most likely candidate, but as I said I don't the full line up of BF. I am glad you are going to talk to BF.