I continue to be very pleased with my Dahon Curve D3. I've pretty much got the bike dialed in now. The pictures show how the bike folds and what I'm using for luggage. I also added bar-ends, lights and a bell to the bike and for better wet-weather braking, I upgraded the brakes with Koolstop Salmon brake pads.
The bike rides really well. Having the bag up front doesn't seem to bother the handling but like most folders, the D3 is not a bike I can ride no-handed. Single-handed riding is fine, however. The Schwalbe Big Apple tires are great, I've ridden them on rough roads and gravel paths and they are plenty comfy.
Speaking of comfy, the stock saddle is cushier than what I usually ride but it seems right for this bike. I'm quite upright on the bike but I've already logged some fifty mile days on the bike and I still like the saddle. The Dahon is such a kick to ride, I'll probably ride a century on it before too long.
I have done a few multi-modal trips with the Dahon, things like taking the bike on the bus from Seattle to Federal Way and then riding the last few miles to a corporate commute seminar. But some folks are doing really adventurous multi-modal trips, like this guy: