I have a Dahon Speed D7 and love it. Have taken it on short trips, multi-modal commutes, and a full 17 mile ride commute to downtown Chicago. From comparing the specs between the Speed D7 and the C7A vibe, I see a few things that you would want to consider:
The C7A is a little bit lighter. If you are planning to carry it a lot it might make a difference to you.
The Speed D7 has a cro-mo frame. I don't know if the ride quality is much better, but I like the idea of the tougher frame personally.
The Speed D7 has more flexibility in riding position, what they call "flex-adjust". Basically you can adjust the height of the handlebars to give you a more aggressive riding position
vs. the C7A, whcih has a single riding position, what they call "neutral"
