Not only that, I finally found the thread, and like Max said it was posted in the Dom2 forums.
Actual testing sounds difficult. Maybe start two nations on an empty massively huge map, one with dom2, one with dom1. Dom1 nation builds 5 temples. Then prophets or pretenders for the two nations teleport to adjacent provinces in the middle of the map where temple dominion spread has not reached yet?
Or just ask lch.
