Irish melodeon players use a variety of one rows from many sources.
The Great Johnny Connolly used Hohners for years until he got a hand made box. His music is no different.
Brendan Begley uses a Castagnari melodeon (MAX)
These are excellent boxes but a clumsy air button arrangement.
Other players are using Quebec made boxes and some are using USA made boxes retuned and the Castagnaris.
I have owned all of the above and I play primarily Quebec and Irish music.
It is a rare Irish player that has much of a tremolo
most are dry tuned or a whisper of tremolo.
However in traditional Quebec playing (until recent years..) one middle reed was 5 cents flat and one reed was 5 cents sharp..so playing Irish sounded odd.
If you get a Quebec box specifiy A 440
I got a handmade box tuned that way and though rare and expensive , never liked it. It was retuned and was a brilliant box. Of course Binci reeds and a handmade bellows helped along with some other details peculiar to Quebec boxes and the particular maker.
My recommendation is to go for the top end and check out Melodie in Quebec.. or retune a Hohner..
Yes a lowly 114... lots of great music has been made on these.
Just as the Quebec guys specialize in Quebec boxes the Cajun builders specialize in Cajun boxes
And Quebec boxes are closer to what the Irish players are looking for without the retuning.
I do not recommend the Castagnari other than it is well made and very light and very fast and very small... it's just that air button and the Euro exchange.
As to lower button height, flapper placement and so on .. incidental but may be true.
I Totally agree with Jefe excepting that if you order a Louisiana made box and specify Irish tuning no retuning will be necessary. However, Irish boxes I have seen did not have the bassoon or piccolo reeds. Just two or three sets of middle reeds. Please note however that I have not seen everything.