On Thurs Night, 17 Nov, I brush sanded and put on the last 3 dusters. Friday, I pulled down all the plastic and painter's tape, and turned the projector on. Put in Avatar in Blu-ray, and it looked great. I then put up the 8 inch board of melamine that I sawed off in the beginning to see if I could tell what difference the paint made, if any.
With some ambient light on, which included some cans that hit the screen, I could definately see where on the plain white melamine, the light washed away some of the image. While the light washed away some of the image on the painted surface, it was not nearly as noticeable, and the improvement could easily be seen. When I turn off all the lights, the difference was only really noticeable in dark scenes, where the blacks were clearly darker, and the image had more depth.
My wife came down and even commented how great it looked, and she never indulges my video/audio purchases/projects. She and my kids both commented that the image looked 3D, and my wife also noticed the differences with the lights on, and in the black levels with the lights off.
So for anyone debating whether to paint your white melamine or other screen for that matter, I can definately say you will see a noticeable improvement in ambient light conditions and an improvement in dark scenes in controlled lighting situations. Again, these improvements are noticeable within 24 hours of applying the last coat of paint.
A big shout out to pb_maxx for all his help along the way. Aug