My gut feeling would be that any euro accounts held by citizens within the Irish state would be subject to conversion to the new Irish Punt, no matter what bank they are held with, eg Rabo, NR, NW(uk) etc, since they are all operating within the Irish state.
It also doesn't seem credible as Happy Girl was told that "it is irrelevant whether I lodge with Rabo in Ireland or the Netherlands as monies all go to the Netherlands anyway." Surely an account opened outside the state and held directly in the Netherlands would not be subject to Irish legislation (and therefore not subject to new Punt conversion). That answer from Rabo appears suspiciously circumspect and perhaps designed more to allay fears of possible widespread withdrawals than to disclose the truth. And if indeed it were the case that "legislation would have to be put in place to legislate what would happen to such funds", I think we all know already what Mr Lenihan's legislation would look like.