Very good advice lads.
I had decided to get the 9.30 Aircoach which would get me into Dublin Airport at 10 for an 11.35 flight. That would give me 95 minutes, instead of the 75 recommended by US Airways, but less than the two hours recommended here.
As it happened, I got up early and was ready to go, so I went for the 8.30 Aircoach. It arrived at 9.07 - 37 minutes late. Had this happened to the 9.30 Aircoach, I would have not made my flight, although I would probably have hailed a taxi after 10 minutes late.
9.27 got to the airport
No queue at check-in or baggage drop - so got through that in 5 minutes.
Long queue for ordinary airport security
Shorter queue for additional US security - seemed a bit disorganised
Massive queue for US Immigration.
11.10 got to the gate
So it took 1 hour and 43 minutes instead of 1 hour and 15 minutes as recommended by US Airways.
The did call people out of the US Immigration queue, but you would have needed to be towards the middle or front of it to hear them calling your flight.
The guy managing the queues told me it was always like this. And indeed someone joining our party a few days later, said that his flight departure was delayed due to the delays in US Immigration.
I suspect that since the introduction of online check-in, the queues have been moved from check-in to US Immigration.
So, I think that the minimum should be 2 hours, so that there is no panic.
Brendan