I live and ride in SF. I ride a fixed Swift. While I obviously can't go up the killer hills with a 67" gear and 165mm cranks, the Swift does, however, climb solid, silent, and responsive up any of the hills I point it at. On my suburban commute, I easily keep up with the roadies on the single climb (overpass) of my route.

Had a Dahon. It was the uninspired climbing/sprinting characteristics of the Dahon that made me scramble to buy the Swift. Granted that with a low enough gear, you could sit and spin up hills, but you're really missing that whole other dimension of being able to rip up the hills rocking the bike from the drops (or flat bars w/ends, whichever you prefer).