I have read the that down pitch tends to push the stock up into the face on recoil. I guess that up pitch would tend to let the stock move down on on recoil. If so, that could be good for trap shooters, as they fire a lot of shells in a short time span at rising targets. Requirements might be different for trap doubles and bunker shooters, as they need to stay in the gun for the second shot.
If the targets were always high, as in driven incoming, then up pitch could be more comfortable than neutral or down. Shooter would not have to band back as far to keep full contact on shoulder.
