That's right, Jon. Most Irish players of two-row button accordions use a semitone-apart instrument, not a D/G job, more "chromatic" than a D/G, and they play across the rows. But the use of the bass buttons is not precluded: as a very fine example, listen to the playing of Jackie Daly on his seminal solo album, Music From Sliabh Luachra Vol. 6. His spartan use of the bass buttons on several tracks is deadly!