Minor update on this- They are available in any facing a normal Link is (though Babbett got caught on the hop by the success of these pieces and promptly sold out of more of less everything- making them all pretty tricky to get hold of at the moment).
Sound-wise these have a huge chamber, making them extremely dark toned by the standard of any mouthpiece. I've only had about a 10 minute toot on one but the whole thing felt very old fashioned in sound, very little edge or bite to it's tone but a nice, big warmth to it.
Can't really comment on it being stuffy or airy as.... well.. I'd never really considered default Links to be that way inclined, so I'm problaby not the guy to ask.