The crank on the Dahon can be replaced with one that has replaceable chainrings since your talking about future upgrades anyway...

I've had a Dahon, Brompton clone, and Bike Friday. The only one of those that rides as well as my Swift is the Bike Friday but it cost double...

The trade off seems to come down to folded size vs ride quality.

I'm sure people could argue for months over it but you'd be able to quickly tell if you test ride them side by side. Unfortunately I can't imagine that'll be an option for much longer with the Xootr being discontinued.

Not sure where your located but there is a local shop in Philly that has a Xootr in stock to test ride if your close to there...