It was an experiment of mine last year. LGW-DUB-ALC with FR on two separate tickets, of course. The cost of both was less than LGW-ALC direct and I was looking forward to a pint of Guinness during the transit. However, DUBHUB security was closed when I got there so I had to exit the building and come back in through Security again. Just managed to make my connection, won't do that again!