From a technical perspective I prefer using subdomains, as it means I can move stuff around or break it out onto separate physical machines if I need to.. redirecting a folder / directory to another machine can get very messy
So basically you're saying that there's very little difference ....
If you were in my position, considering the two domains - what would you do?
I'm not so much concerned with the Irish market, but the general idea of focussing on one domain (if that makes sense)