The Treks are made by Dahon and fold pretty much the same as a Dahon. The F600, the one with the Bontrager Select wheelset (they look like Rolf wheels; to few spokes it would seem), is the better choice and looks to be a sort of marriage between a Dahon Helios SL and a Giant Halfway. Since it's full forked and stayed, I'd call it a Giant Wholeway, or maybe just a Giant Way.
Anyway, The Trek 600 is a fairly well specified bike that's not very heavy(22lbs I believe) and should ride pretty fast and pretty well. There's a few of them around very inexpensively at bikeshop closeouts around here. I saw one for $435 just the other day on Long Island. I haven't ridden one though, so all comments are from afar.
DG1