Aer Arann have a great and friendly crew. The ATR-42 are very old and are rarely used to my knowledge on the Aer Lingus Regional routes. I would imagine that this maybe due to technical/maintenance reasons to reduce delays.
EIEHH which was the latest ATR42 to join their fleet was in fact an ex Air Wales aircraft G-SSEA
ATR-72 are more modern however not so sure about the EISLL, EISLM, EISLN aircraft that have come in from Air Contractors.
I hope Aer Arann continues with the excellent service