Dunno where the statement that the A330 is not a sensible aircraft to be using from SNN to JFK came from? However, I've been very reliably informed that it is indeed perfect for the route as well as SNN BOS, DUB to JFK, BOS, MCO or ORD. And before anyone jumps in and says that the loads are not good outta SNN I can also tell you that they are. In particular the BOS to SNN is out performing the BOS DUB for the third/fourth year in a row. SNN JFK with both DL and EI are holding their own and doing very well with near full flights. I believe their business cabins are only doing ok though as well as CO to EWR. But business class cabins to and from DUB and many of the major european hubs are suffering the same hit.
DL pulling outta SNN is probably very understandable as with the economic downturn the west of ireland can only be seen as a seasonal route and having two carriers on the one route or three if you include CO on EWR route is very likely too much for the market. One carrier operating should be enough for the winter or at least this winter anyway. But it shouldn't be a 757. Either CO bring in a 767 to operate daily if EI don't operate to JFK this winter or else let EI and CO hammer it out with every second day operations or something. Sounds a bit too idealistic I know but it's worth a try.