James didn't try to rule England from Edinburgh, so it would be strange to assume that Britain would be ruled from Dublin in any such scenario. England would be the wild lion in that relationship and you'd need the royal court to be in London to keep control of it all. If you were permanently in Dublin, that leaves some ambitious little regent running England from London on your behalf. It would be like trying to rule Byzantium from Sicily instead of Constantinople. Not exactly smart.
Yes and who would chose to rule an empire from Sicily ;-)
Sorry it was to easy