I have done some calling around. Dillon's has sold everything they can get their hands on. My local dealer (Lowell, MA.) is being quoted December delivery for Prestige horns ordered now. However, the 967 and 968 Sovereigns are available. There is a 967 in stock at David French Music in Westboro, MA and 968's (and 967's I think) at Dillon's in Philadelphia. While there are some differences with the Sovereign vs. the Prestige, I think you can get a pretty good idea of how they play by playing a Sovereign.
The new "Buffet" horns play VERY nicely. All the feedback I am getting and my own audition of one suggests that the new horns (built in a JA Musik factory that also builds Meinl-Weston tubas) have superior valve action, great response, good intonation, but a little lighter tone than the prior generation of Bessons. (I know this to be true in my own tryout in comparison with my 1st generation 1980 Sovereign).
Doug