I'm a little late coming in here, but have to agree with DL, out of all the years we have raised Maine cattle and the thousands of carriers I have seen, I can honestly tell you I don't see any difference or benefits of a PHA carrier. That being said, I like Irish Whiskey, we bred a large number of our Angus cows to him this year trying to get some clean replacements out of him, I didn't breed to him to get the carrier "look" I bred to him because he is a stout moderate framed animal I happen to like, same reason I breed to Anchor on the Angus side.
I will have to say on the clubby side, if you want the look, it comes right now with the th carriers, don't know if it's because they are carriers or if it just happens to be a coincidence, but there seems to be a connection there in my book.