I was also at the Sunday Parkways (on my Birdy) and also saw a few Bromptons. I agree about the wait, though. I was down in Portland with a friend who was picking up his - took three months to get it.

We spent the day riding through town switching back and forth between my Birdy (has a Nexus 8) and his new six-speed Brompton. While I still prefer the ride of the Birdy and the Nexus (the 3x2 shifting of the Brommie is definitely a bit annoying and the ride is inferior though not bad), I'm super impressed by the handling of the Brompton with 15 or so pounds in the front carrier. The Birdy carries weight well if you're in touring mode (4 panniers front/rear), but the Brompton with its big single front bag is brilliant from a convenience standpoint.

I didn't really see the point before, but now I'm thinking of getting one for city use. If Brompton can build some extra production capacity I think there is likely a US market for the thing.