Just because you're travelling in an Irish passport doesn't mean you're travelling from Ireland. And as I understand it, from October 26th existing Irish passport hoildera are going to have to get visas.

It might be best not to trust that US embassy statement about UK passport holders not needing visas after that date without checking further. A bit late to find out they'd got it wrong when passport control sticks you on a plane home when you land there.

I've never had to show my passport in or out to other countries in Europe in recent years. Been bodysearched, but they didn't bother about looking at the passport.