We have remarked that Being, which for Plato is at times at least less than the Good or One, must be understood as finite Being. That this is the general classical view is stated by a number of modern commentators, not all of whom are prepared, however, to see what it implies for Plato and Plotinus. Fr Seeney, for example, rightly quotes with approval the remark of Fr Owens that 'Perfect Being for the Greeks meant limitation and finitude,' without at the same time admitting that to place the One beyond Being means for Plotinus simply to place it beyond finitude, to make it intrinsically infinite. Similarly Gilson regards the One beyond Being as a non-existent One. For these interpreters questions about the finitude of Being in the classical sense of the word do not arise. But here we may be merely playing with words. The question before us is not whether Plotinus said that the One is 'beyond Being,' but what he meant by saying this. And in view of the general Greek use of 'Being' to mean 'finite Being,' the prima facie meaning of the phrase 'beyond Being' should be 'infinite Being.'
-- John Rist, Plotinus: The Road to Reality, 24-25.
The relevance of this passage to Orthodox-Catholic dialogue should be obvious to the attentive reader! This is a point I have made in debate more than once, to little avail, I'm afraid.