Thanks for the replies.

The Airnimal is a great suggestion. Pretty old post but it appears its still for sale. A long way from me, and no chance to ride it though.

The Xootr Swift is nice and close. Not as compact but I suppose I could live with that. I don't commute but I do need to fold it and put in my trailer or pickup box. Ideally I'd have a more conventional fold, but really like the idea of a upgradable bike and full length wheel base. Can 451 wheels be fitted?

Any comments on the Dahon MU SL?