Interesting that article doesn't refer to APD as far as I could see. Maybe it's because the potential fare saving can only be achieved by buying separate tickets XXX-DUB and DUB-YYY, but I assume that doesn't guarantee your connection or being put on another flight if you miss the connection. The big selling point is therefore the pre-clearance and what they allege is less hassle.
I doubt too many folk would choose to fly MAN-JFK via DUB as opposed to direct but I guess MAN-SFO via DUB could be quite attractive. Incredible that EI will have a daily service there this summer.
Out of interest, how much transfer time is needed to allow for the pre-clearance?