I highly doubt "lifestyle choice" was that great of a deterrent factor for potential Northern Irish refugees. I think it was the fact that the average NI citizen did not feel threatened enough by daily violence to make leaving worthwhile.

Everyday British citizens, while they did have to live with an ever-present Irish terror threat, never died at anywhere near the rate that American soldiers are dying in Iraq today.

Note also that the British ended by negotiating a settlement with the enemy, not defeating them.