I think you should consider the Bike Friday Pocket Expedition. The 20" wheels are plenty strong. It folds smaller than the Dahon and Swissbike, has a low stepover height, and it's made for traveling. The suspension seatpost and fat tires make it comfortable. It comes in a small size, so it may fit you better than the other bikes. You might also like the low stepover height. At a list price of $1195, it's above your stated budget, however.