A better alternative 16" CrMo folding bicycle is the Langtu QY018. In addition to a smaller pricetag - $360 (vs $450-$500 for the Dahon D5) - it has rear frame spacing for a modern cassette hub.

The only known downside is that it has just one pair of rear eyelets. Have to double up to implement both a rack and fender on the rear. I can live with that.

The only unknown to me is whether it can use Dahon/Fnhon handleposts or not. The one it comes with has two bolts for the clamp that secures it to the fork steerer-tube and looks taller in this area, compared to a Dahon/Fnhon handlepost.