I'm just saying that if you look at their descriptions, and the different screen materials they offer, their lineup does seem similar to da-lite's. Maybe not the same, but if not then someone is in for some copyright trouble.
I think it would be difficult to copyright the typical descriptions used. It's really hard to evaluate similarities in the screen construction much less material without looking at both to do the comparison.
To the original poster, Stewart does many things well and it's fair to say they're are the industry standard to measure by. It's hard to answer question of value without doing a comparison of fit and finish, uniformity of screen material and user experience for you to personally come to a conclusion. Having had some experience with various types and brands of screens, it requires more than comparing specs on paper as there are issues beyond just visual similarities to take into account in deciding what would matter to you.