Just to let you have some info on the population, the republic will probably be just above 4.5 million come the end of the year, whilst NI has just become 1.8 million giving a grand total in the region of 6.3 million.
Also although the recession has reversed migration, natural increase has ensured the population of the republic has had continued growth through the fiscal downturn.(Albeit at a slower rate.)
I now live in London myself, and have flights booked with BA to New York during the Royal Wedding weekend (had to take advantage of the extra bank holidays
) but would have loved to try the pre-clearance at Dublin!