I think people are getting confused. Aer Arann and Aer Arann Islands are two seperate companies. Aer Arann Islands are a small operation flying Islanders to the Arann Islands off the west coast of Ireland. I somehow doubt that they consider OAT low hour guys as this company is a single crew VFR operation. You need a minimum of 800 hours I think as per JAR regulation.
Aer Arann on the other hand operate a fleet of ATR's on domestic and european flights and are completely seperate. They consider cadets from all schools including OAT and the like.
Just my two cents worth. May help to avoid the confusion.