I was thinking the Adams groupie thread had gotten so long that it might be useful to start another.
I've been playing an Adams for a year now, first a .6 thickness sterling large bell, then the .6 thickness smaller sterling bell. Much different horns. The large bell is one of those powerhouse, play over any ensemble instruments. The smaller bell has less dynamic headroom, with a more focused sound. Nothing unusual in that respect in the bell size department. I now play only the smaller bell instrument and will stay with it, although there are times, usually when I play in a brass band, when I just want to play louder. But most of my playing is in wind ensemble and chamber groups, where the smaller bell excels.
I find the same intonation issues as others; the instrument plays flatter than most euphs when cold. I generally start, in cold weather anyway, with the main slide all the way in, then usually have to pull it a 1/4" to 3/8" once I have played a few minutes. (However, that tendency was great when I played a church service recently with pipe organ accompaniment by a organ which was 25 cents flat!).
The instrument is in good tune with itself, in that one can lip the notes where they should be, especially if you hear the note in your head as you play, working to use heard just intonation as part of an ensemble rather than the non-optimal equal temperament of a tuner. Depending on musical context, I sometimes have t use 1-3 on the 6th partial e flat -- but not always -- and that's it for alternative fingerings.
I've run through a lot of mouthpieces trying to get the best sound. I now use the PS Solo most of the time, getting a rich, warm complex, sound. For a brighter, more cutting sound, like doubling on the octave with trumpets in a Latin piece, I'll use the SM3X.
There is really nothing to dislike about the Adams, for me anyway & for the kind of playing I do.