I've played the box for nearly a week now, and thought I'd share some initial impressions since I haven't seen anyone else on the forum mention having bought one. I was initially apprehensive about the investment, given that it costs nearly ten times what my starter cost, and practically speaking I can't expect it to be ten times better, so there's some expected diminishing returns as price climbs. I fretted I'd feel I overbought, or maybe that I'd feel I'm just not good enough at concertina to justify buying a pricey one. I suppose my current state is "cautiously pleased".
The box is largish compared to an Anglo, but no larger than the 34-key Elise, so no problem there. Also as noted by owners of other Morse models, it feels very light in the hands (3.1 pounds); not flimsy, just it is quicker in the hands than the size suggests. I don't feel ready to compare tone yet, since I've only heard it through a "player's ears" so don't know how it sounds compared to an Elise on a recording or to an audience. Further, my Elise has been "played-in" for a few years, which I imagine has helped developed the tone, so hard to get apples-to-apples. I might need to do a double-blind test with friends to ask which they think sounds "better", though some forum members have mentioned their bandmates prefer the sound of their Stagi over their Wheatstone, so subjectivity.
The upgrades that led to the purchase, however, are immediately apparent. The action is way crisper on the Beaumont, keys bounce back much faster, and the reed response is much faster and smoother. And it is convenient to be able to be able to play in Bb and A as easily as I played in C before. That said, even an expanded keyboard has its limits, as I found when I tried to work out a tune off a recording (May Blooming Fields, done by Cordelia's Dad), only to find it's in F# and so requires bouncing a finger all the way across the keyboard to get the one note (Bb/A#) I don't have on the far right. But F# is not among my favored keys, so I'll survive. The width of the keyboard does take some adjusting to: with the straps snug I can't reach everything, so I have the straps a little loose and "cup" my hands to take up slack when I'm not reaching for far notes. The straight (rather than canted) keyboard is taking a little getting used to, but it does indeed make it easier to reach the sharp side of the keyboard.
The bellows are of course way nicer than the Elise, though mine are going to take some breaking in. My Elise feels loosey-goosey when played back to back with the Beaumont, both in the good and bad way, but presumably the Beaumont will take on more of the good-loose and little of the bad-loose as the bellows break in. I'm finding the air button on the handrail to be a fun change, but the airhole is very small: while holding it down it still takes a few seconds of pressure to fully open or close the bellows, it's not a big gulp of air like on an Anglo. I presume this is deliberate, and it is to some degree helpful since I can take a quick breath to set up my bellows for a long push or pull but use so little air that it's easy to keep it from affecting the notes underway.
This is what's popped to my attention over the few days of playing; I'll probably have more realizations as I mess with it. I do feel that this decision is helping me to double-down on learning duet, to the point that I'm selling off some excess gear since I'd rather invest the time in learning concertina than in improving my limited clawhammer banjo skills, etc. I like the sound of concertina, it gives me a lot of the traits I would've bought an organ to get, and I think it's a great instrument for song accompaniment. I'm coming to the conclusion that I want to get better (or if not better, at least more confident) at singing, so I can make good use of the concertina as accompaniment.