Nah the ferries are the same. Built for the conditions and skippered by blokes that know what they are doing.
But if your moving the Mrs up I would suggest that you send her by plane and you and the kids go by boat the first time. I used to love the boat as a kid.
Its a cracking place to live I presume your Irish so you will have no problems fitting in with the community.
And the St Clair was better than this new one in my opinion.