Thanks. The landscape is very, very flat where I live, so low gears really don't matter -- but keeping up with car traffic does! I'd definitely stick with the 3-speed hub -- my primary use for this bike would be to retrieve my full-sized bike (when I've left it at my office due to rain, or when it's been in the shop, or when I've decided it would be smarter to walk home from the bar...
), so I want to be able to strap the folded bike to the rear rack without a derailer sticking out to bend/break.
I just bought, tried, and sold a 20" Dahon Getaway -- it just seemed a little too big for the purpose, and the single-speed gearing felt a little too low for comfort in traffic. I'm looking for flat-out speed in a tiny folded package, but I can't afford a Brompton. I'm thinking that the Classic III, upgraded with high gears, alloy rims, and high-pressure tires, might do the trick. Any other suggestions?