if that's what you are after just to be able to pull it behind you then i think the brompton is the only way to go. but if you want ride quality then there are alot of other folder choices out there. Plus is pulling behind you that much of a necessity? because dahon came out with a really neat shoulder bag that you strap onto the wheel and frame and just wear it like a bag. The best part is the bag is tiny and fits in a mini bag under your saddle for commuters.
http://www.youtube.com/watch?v=WZOLQD9hb6c