Sharron Shannon was the ONLY Irish accordionist to play a Castagnar 2 row.. though others play the one row..
She played primarily Tommy's in B/C and C#/D as well as the Lilly 1 reed..
Stepped keyboards are unusual in Irish style of play...
One was played at an Irish festival recently in Chicago and opened alot of eyes and ears... A reputable irish box collector/trader recently contacted me as he had heard on in the States and says they are getting popular in Ireland they say.
Pro boxes.. not for amatures.. great tuning..great action.