I've had both on my Ericsons and both have plus and minus, so for me it's a dead heat.
I think what this means is that if you have a solid vang and need to turn it, there's no great loss. Neither orientation will keep spray out going to windward in lively air, since the water comes in either way and the hatch has to be dogged closed, no matter how stifling that can be (thank goodness for the twin dorades on the E38s)..
Forward-facing is probably better at anchor in Florida or Annapolis in summer, when vast volume of air is needed.
Yeah, but wait a minute--if the forward hatch is open, maybe with a wind scoop, a reversed main hatch would probably draw the air out better than forward-facing.
I am arguing with myself. But trust me, I am right.