The problem we have is that most people don't know why and when to use screens and why to use different shades of screens.
Grey screens are excellent for use in poor rooms, but a dark theater environment actually gets zero improvement from specialized screens and they just suck up money which doesn't need to be spent. Both the Firehawk and the DaLite High Contrast Cinema Vision are cheaper positive gain, grey screens which improve contrast ratios in rooms with uncontrolled ambient light. The Black Diamond and DNP Supernova screens are designed for use in high, uncontrolled, ambient light situations. Specifically, those two black screens were designed for board rooms and commercial installations where ambient light is a huge issue. That's because they maintain incredible contrast ratios despite the horrible conditions of the typical boardroom.
That's a big caveat: They MAINTAIN contrast ratios. They don't improve them, they don't improve the projector, they don't improve the room.
So, in a room which doesn't need help from a screen, a standard grey screen does little, a pricey (very pricey) Stewart Screen adds nothing, and the comparable, but far less expensive DaLite HCCV screen performs similarly. The key is that the room itself doesn't cause deficiencies in the image, and proper lighting maintains that incredible image on screen, so the best screen is one which doesn't screw around with the image, but preserves it in the best way possible.
Most people still jump to expensive screens as a solution, without first determining if there is a problem. You almost never try to pair a screen with a projector. That's silly. You pair a screen with the room. You buy a screen to match the room and the viewing requirements, not a screen which goes with a projector. If the room is good, then the screen doesn't need to correct the room, the screen only delivers the image as perfectly as possible.
The worse the room is, the more screens like the Firehawk and Black Diamond become important. But, the best image in a poorly lit room on a great screen will look worse than what the JKP Affinity screen and the same projector will look like in a great room.
Room>Screen>Projector
Want to make a $2,000 screen/projector setup look better than a $10,000 screen/projector setup? Buy $50 in paint.