John, I'm not in the market & forgive the stupid question but I am curious.
I was looking at a couple of Tenors recently, but both had only 35 keys, so I'm just wondering how come your Tenor Edeopone has so many keys?
Is it a Tenor / Treble or just a Tenor with a lot more options?
I don't know if Lachenal had different terminology, but in old Wheatstone price lists all "tenors" seemed to be listed as "tenor treble", whether they had 35, 48, 56, 64, or some other number of buttons. The common factors were that that their low note was C below middle C (giving the "tenor" part of the name) and their fingering in the treble range was the same as a treble (hence the "treble"). I.e., they were trebles extended downward, with differences in the number of buttons reflecting differences in the top of the range. I suspect that if the term "tenor" was used, it was simply a shorter synonym for "tenor treble".
More recently, it's become common to refer to tenor-trebles with 48 or fewer buttons as simply "tenor" and those with 56 or more as "tenor treble". (If you find one with more than 48 and fewer than 56, I'd like to know more.)
From what I've heard, the 35-button "tenors" (or "tenor trebles") were mostly intended for concertina band use, especially for marching bands, where the parts played didn't go especially high but reduced weight could be desirable. Also, the few I've seen tended to have larger reed chambers... for a more "robust" sound?
I'll be interested to hear what John has to say about such terminology.