Not just in N.A. : I happen to use the Brompton to travel, and finding even inner tubes is impossible outside major cities, where Brompton retailers can be found.

I'd be curious to know how different a 305-based folding bike rides compared to a Brompton. At least, 305 wheels/tires/tubes are much easier to find.

As for the Brompton vs. Dahon/Tern or even BikeFriday: If you need a 1) really compact folder that 2) folds in a few seconds, there's just nothing else at this point.