No, I'm not an expat at all, still 100% Dutch and as I left my house and work 9 years ago, I really am outside the system here.
However I have loads of work as a gardener and handyman amongst other jobs and live with friends.
I visited Ireland for 3 months back in 2011 at my family though and worked in an animal shelter while I was there.
My ID cards were still valid back then of course and I had no trouble crossing the border, even though I sweated a bit on my return as I had alot of debts from my house that I left.
The issue currently is the Brexit, which will make travelling alot harder for any residents and just wanted to point that out, as you might leave now without much issues, but you don't know what those government idiots will cook up next and any extra customs control they could impose.