I did some research on this very topic recently. Dahon curve's specs are absolutely perfect but handing off such an expensive bike to a kid wasn't going to happen. Ended up with an ancient Dahon ancestor, actually the first Dahon I think-- Dahon Classic. Seat and handlebar are adjustable, has front and back handbrakes, 16" wheels, and an internal 3-speed hub that's geared just right. It even looks stylish at least to me. Of other bikes I considered, I came close to buying the Citizen Tokyo but I found that the idea of a derailleur that nearly grazes the ground bothersome, and I read too many reports that the six speed is geared too slow.

That said, the Dahon classic is so old that you've either got to be lucky or know how to examine a bike before buying. In retrospect, I probably should not have bought one of the two that I did. But if everything is functional, it is really difficult to beat the fun of riding this old bucket. And I can't say enough about the 3-speed hub as it spans a nice range of speed and effort well.