I finally had a chance to visit the wonderful Dillon music shop - amazing shop! They really have an amazing band instrument selection. While there, I got to play their DMB-1067 euphonium - all the specs for this, large shank, bore, bell, nearly everything had identical specs to my Dillon 967 - but it is non-compensating. The valves are blazing fast - faster than any compensating euphonium. And the low range responsiveness is what I always wish compensating instruments would have. Tone is essentially identical to my wonderful 967, which is to say it is GREAT - dark, rich, and broad.
Here's the deal with the low range intonation (concert pitch) - the Eb was just a hair sharp with 1+3, and the C# was just about perfect with 1+3+4. I could pull tuning slides to get an acceptable D with 2+3+4 or get the C with 1+2+3+4 - but you can't have both the C and D to be reasonably in tune at the same time - a compromise makes the D very flat and the C very sharp. Unfortunately, the Bach cello suites I primarily play on euphonium does require an in-tune D and C in the same piece - that is the only reason I didn't jump on one of these immediately for myself.
However, my kid is 1.5 years into euphonium (after having spent a half year miserable on trumpet) and hasn't had his own instrument yet. He liked it and preferred it over Dillon's Yamaha 321 clone and the Yamaha 3 valve euphonium. So, he is now the proud new owner of the wonderful Dillon 1067!
These are wonderful instruments! With all the recent talk of the new Adams sonic, after trying the Dillon 1067, I continue to believe that unless you plan to study music in college and/or become a soloist playing the most demanding repertoire, the compensating system just isn't necessary, and the faster valves and improved low range response are definite benefits to go non-compensating. I think it is great that companies are offering wonderful non-compensating instruments alongside their compensating brethren. For years, if you wanted a large bore/bell instrument, you had to go compensating - and having choices is a very good thing in my mind.
I had one for a while as a second horn. It's a very good clone of the Besson Sovereign 967, both in paying feel and sound. I sold it because I was playing an Adams E1 pretty much exclusively.
Oops, just a quick later edit: the euphonium I had was the Dillon 967, not the non-comp Dillon euph in the original post.