I like this bike, looks wery simple to fold, no der to worry about.
About weight: I went to the site a few days ago. Used the translation option and found they have three different models, and I got the impression each model was in its own colour. Think I remember a 7 or 8 Nexus hub with rack and generator hub as the top model, maybe a three (or two) and one speed for city. They would all have a different weight (and price) so maybe find out price specs and weight for each model before comparing to get it right.
Edit: Looks like the blue is chain only, the two others have belt in the pictures. Nexus7 hub on the copper one. I signed up for newsletters by e-mail.
Edit2: More info here, especially the user manual is cool! Found a black and a white coloured bike in there also. There are special guides to keep the cables away from the hinges when folding.
http://www.btwin.com/en/home