Bikestoworkny- I've had the cheap Dahons (Boardwalks) and the Downtubes. For the money I'll take the Downtubes as it is nice to have gears to adapt to the terrain you are riding on and some suspension. In general I've had spoke issues with the cheap Dahons. They tend to rust pretty quickly for me.

The weight isn't as much of an issue unless you are carrying it a lot or have trouble putting it in the back of a car. A lot depends on how much you want to spend of course. For the $200-$450 range the Downtubes are the bikes to beat.

If you buy a cheap Dahon (i.e. Boardwalk) they have cheap spokes, crappy seats, no suspension and all around pretty low spec components. On the plus side they are cheap, have fenders and a rack. One thing you need to decide if you want internal hub gears or a derailleur. The internal hubs on the Downtubes far outclass anything else in this low price range.