I have seen Chris' concertina, I am a "newbie" and didn't realise that some Maccanns started on 'C'. I have a New Model 55 key, with all leather bellows. I have a bit of frustration trying to play tunes without going up an octave, (although I should be used to this as I play recorder, mainly soprano). I sing soprano, so wanted to be at the same pitch. I spent an entertaining couple of hours trying to work out if you could move the keys around on a cheap 46 key (might need a few extras) to get the same effect. Nothing came of that, I don't know how the fingering would work!
I did consider buying Chris's concertina, but can't really afford it. I also considered asking him for a part exchange, but I don't want to part with the New Model I have, partly because it was given to me by my father in law and it's a very nice instrument. He gave us 2 Maccanns, the other was a 46 key with brass reeds and rosewood ends which I tidied up and husband Brian repolished. We sold it on to finance the refurbishment and tuning of the better one by Andrew Norman.
For those interested the numbers are 789 for the 46 key and 805 for the 55 key. Father in law's first wife's mother(!!) was an accomplished piano player, so may have had these in succession.
I have looked at this topic on several occasions, so have totted up some of the 734 views!
I'm sure CA would do a PX and you could come away with an instrument that was exactly what you wanted for a modest extra investment, but I understand the sentiment angle too (It hadn't occurred to me before that there were downsides to inheriting an instrument.) You don't think Father-In-Law would understand you trading for a similar but better instrument though? Wouldn't he just be pleased you were playing?
I added a brass reeded 46 to my bigger instruments last year as a portable 'rough' (well you know what I mean) instrument. (for walking and sailing and beach barbequeue type events) and I understand completely the point about having to lift the tune an octave higher than sounds best. It's a bit obvious I know, but sometimes you can drop an octave if you take the lowest couple of notes into the LH and thus avoid using the 'dog whistle' notes; or there's always transposing a fourth or fifth; that means adding or subtracting an extra accidental but may well solve the problem.
Now probably is a good time to buy another one if you are going to; pity we're all broke or sitting cautiously on our money, eh?