I don't choose to use PS photomerge because it isn't particularly flexible about setting the projection you want and, more importantly, setting the center/horizon point. This means that panos that are directed steeply downward or steeply upward will have distortion that you can't modulate to your pleasure.
That's something I had never even thought about. Great pointer.
Sure to try this out in the future just to see how much it messes with my eyes