Has anyone done a trip like this in either direction? What was it like? I can't believe my eyes that it is only 46 euros. My main concern is that I will have a child recovering from a long illness and a (hardy) senior citizen with me. I am reasonably patient with delays, etc, but would like to know if the system is timely and reliable most of the time. Looks like airfares are slightly lower from SEA->DUB than SEA->LTR. Also, we get to experience Ireland! Here is where I got my info: http://www.seat61.com/Ireland.htm
A colleague of mine is from Dublin (but works with me in London). He has used the SailRail and says it's fine, but it takes 8 hours and so he usually flies. It may be a bit more expensive if you want a decent airline (which, for example, doesn't charge extra for checked luggage or allocated seats), but it's only an hour in the air. If it was me I'd go for SailRail because I love trains and ferries. Whether it's likely to be on time depends mostly on the Irish Sea, which can be rough, especially in winter but potentially at any time of year.