I have listened to a pair of Orions. Generally, I've been particularly interested in open baffle spkrs for quite a few years (ever since I listened to "Audio Artistry" spkrs, also designed by Mr Linkwitz) and have frequented the Linkwitz site assiduously.
Following your questions,
they are the closest thing to live music available
I would rather say, they are very close to what is contained in the source material -- what comes out of the phono or the cdp, etc. Having read some of your posts I think you understand the difference. There is an easily perceptible lack of distortion and, an impressive simulation /rendition of dynamics. The dynamics surprised me: the drivers used are quite conventional (OK, selected for their linearity and distortion characteristics, but still off the shelf);
the implementation extremely complex (the xover, 6-8 amplification channels).
Still, the dynamics reminded me of horns -- i.e. far away fm panels.
excellent sub-bass response within an open box
No, they won't go that low. IMO it's a good thing: bass (& sub-bass if necessary) is best implemented independently and separately, away from the main speakers in the listening room.
a very slender and elegant cabinet
There is a good point here: given the sound they produce, the speakers are quite reasonably sized.
Please note that the Orions I heard had the front tweet only. Lately a back tweet has been added.
Cheers
