Im sorry and this is nothing against DUB/SNN in particular, but, I just dont see what the fuss is with this pre border clearance?!?
You still have to go through the same passport check procedures, you still have to queue but instead, they take your duty free allowance!
Yes, at the moment the queues are slightly smaller (at the USA I have personally never waited longer then 10-15 mins, and Ive arrived with a few international flights at once too), and the more and more flights that use DUB for the pre-clearance then negates the time saved as more people are queuing.
Then to DUB itself RE AI, I still think AI should go for BHX as a hub. The runway isnt that difference from DUB, but at least there is a huge population to support it (more than DUB could ever offer). Even MAN would be a better option, as it has the larger populations to support, and at least cargo could go out completly full.
Then again, has any decision by AI ever made sense?