Hi,
Jeff Bookwalter lives very near Columbus and he owns a set of Orions and Thor subwoofers. I've been trying to get down there (I live in Cleveland) but work and family activities keep delaying my meeting with Jeff. A great guy and from what I've heard, a great host as well. His contact info is on Linkwitz' website. If you get to hear them, post a review.
I've heard the NaO II loudspeakers in PA but haven't heard the Orions yet. The NaO II's were wonderful, best of all was his cardiod subwoofer instead of the standard H-frame. In addition, I went up to Denny's place to listen to the GR Research OB-5's in Toronto. Another excellent loudspeaker. So far the OB2X, OB7, Linkwitz Orion and NaO II dipoles are on my short list as far as dipoles go. They all are different enough from a design standpoint however. The only common denominator is the dipole tweeter/midrange.
Best,
Anand.