I'll echo SunnF above. Think long and hard about how you will use the bike. If ANY carrying is required, test out the bikes by riding and by folding and carrying them for at least 2 minutes (the time it takes to, say, walk a train platform). I had a Dahon Speed P8 and loved it. I was heavy to carry very far, but it did tuck nicely under my arm for carrying short distances.

If the overall folded size matters (stowing on a train, in a closet at home, under desk at work, etc) then consider that as well. Fold it up and see where in the store you can stash it and how easily.

How fast do you need it to fold? Will you be running to catch a bus or train? Dahons don't fold too small, but they fold fast.

Will you need to wheel it along when folded? If so, good luck on that one for $300