Ed, as always you have personal choice.
I always recommend folks to double check any information and advice they receive on the form regardless.

Look here

and

Here

or check directly with:-

Home Office Nationality Group
(Right of Abode)
PO Box 306
Liverpool
L2 7XS

The EEA Registration Certificate application form itself clearly states it's not mandatory

Do please verify your right of abode with appropriate authorities as I've suggested.

It'll be confirmed that Irish Citizens have right of abode.