Does the posterior maxilla have to me dropped/downgraded if you already have a longer posterior maxilla/skull? In my face I have a longer face downgrading the maxilla would make everything worse.
If you have a long face but normal tooth show, then I'd think three possibilites:
1) The maxilla isn't the problel check your lower and upper thirds
2) Large soft tissues covering large maxilla
3) MOST LIKELY IMO - It could be that the steep occlusal plane is what's making your face look longish and the downgrafted posterior maxilla will actually make your face appear shorter since the CCW rotation would be achieved, because what you see is the front of your face, and the convex profile is part of what gives people "long faces." Also note that as I mentioned in my previous post, maxillary advancement will add to tooth show (gumminess) because you are stretching the soft tissues, so impaction would be performed to offset this.
If you think about a face from profile view and create three vertical sections: back, middle and front... the middle would then be lengthened but the front would be shortened... like a maxillary teeter-totter. And when you talk about a long face, you're talking about the front.
This is how I understand it anyway.