I'm probably known here for my Swift, but I actually also own a 2005 Dahon Vitesse D5. My first folder. I bought it at a time when I had been away from bikes for over 7 years, and didin't know anything about folding bikes at the time, except that I liked the black paint job. I bought the Swift shortly after having multiple problem with the VD5, which were later resolved by Dahon taking back the bike and sending me a brand new one.
The VD5 comes with a 5-speed Sturney Archer internal gear hub. It's horribly noisey (I liken it to a rear wheel when laced to a coffee grinder), and the gear spacing is all wrong (not low enough in the low-end, too wide a gap between 3rd and 4th, and a 5th gear that feels mushy and rattles like heck). The best I can say about the drivetrain is that it's reliable.
The Vitesse D5 is somewhat notorious for "axle-creep": being that the rear axle slides forward in the dropouts over time and under torque. I've since resolved this by retrofitting a RedLine chaintug on the drive-side.
Other mods include a carbon flat handlebar, San Marco racelite gel saddle, and 20x1.50 kevlar Comet tires.