The first two categories integrate into American life quite well over time (I have some of both in my background), but the last category stay brutish and nasty, no matter how much money they get and how much education they're exposed to. I think the Kennedys qualify.
My Grandmother had similar observations about the Norwegians. There were the Dirt Hut Norwegians, the Mud Hut Norwegians (lived in a wetter climate) and the Projects Norwegians. Great Great Great Grandpa was a Herringer. He would take his dragon boat out and harpoon the wily herring. My ancestors migrated to the US because of the great opportunities here and the poor food in the Norwegian jails. My family mostly settled around bars with cheap prices.
Can you dilineate catholic from protestant irish in the milieu? Seems that this features prominently in current anglo-irish politics. Somehow Scotland has separated.