I found in another thread here, not searching just reading through, there was apparently a Curve SL model that Dahon made that has a higher gear range (8-9 gears?). The poster mentioned it was 8 gears but when I searched the Dahon website (had to go back thru Archives - 2011 was the last year they were made - see link) the IGH in that spec sheet is a 9 speed. That would be right in the ballgame, though with a higher gearing shift than I'd like - 32-93 GI, bumping the chain ring down would solve that, though the Dahon's stock crank/chain ring look fairly specialized with the chain guards.

I am wondering how hard it would be to order the existing lineup Curve D3 and get the shop to swap out the hub with the XRF8, if they can get it. There are a few changes I'd like to make off the bat too, though - a drop bar set up (or split it if I have to for brakes/shifter install), petals maybe, and the saddle. Then the crank - I would need to change the chain ring size from stock, as well as go with a different crank arm length. So maybe building up from a frame would be an option? Unless Dahon doesn't deal with anything but "complete" sets.