Calhoun Cycle has all of them. I strongly suggest them.
The Ori has, what, 349s? As opposed to 305s? The best tire in this size, IMHO (and Vik will back this up) is the Greenspeed Scorcher TR (Kevlar).
This guy. Note that this tire (which is a 349-40) won't fit on the back wheel of a Brompton due to stupidities in Brompton's frame design. Works fine on Tikits. I mention this to warn you that you'll need to make sure you can put a 40 tire on your Ori.
The Scorcher is the most comfortable and probably the fastest tire in 349, it's also probably the grippiest, and the TR (Kevlar) version is thorn resistant. But it's likely not a long-lasting tire (as you know, you must compromise somewhere in your rubber compound choice). I've had mine for over a year in pretty grueling situations and it's held up.
If you want a long-lasting thorn-resistant tire, try the
Schwalbe Marathon Plus. Be warned that this is one slug of a tire, and far from comfortable. I for one would prefer to buy new tires every few years and be fast and comfortable.
I tried Brompton's tire once, and I didn't find it to be very comfortable or fast. Might as well go Marathon in that case.