Yes, I feel strongly that moiré is the main issue. It's not just the screen technically speaking, it's in combination with the display as you need both for the interference pattern. Now if the weave is at a diagonal, and the more the better AFAIK, that is a good thing and it should be if it's a good design. You see I just ran a search for moiré at the AVS Elite screen thread, and there are at least 25 hits, pretty much always with the AT screens, and one guy seems to be implying that the weave is not tilted (older design? issue addressed since?). Which pretty much means bad news when coupled with LCD PJ. An LCOS projector has the highest fill ratio, I mean you could tell me it's 99.99% and I would believe you, and so you don't really have this issue with AT weaves AFAIK. What I'm saying is: Would you consider that this screen to be defective if my PJ worked fine on it, but yours didn't? Or IOW, maybe what I really mean is that . . . if I were you I might not play the defective card with them so much, rather than, "aw man I'm really bummed about this, can you please have mercy and throw me a bone".
Another option play to consider with your vendor as a compromise (depending on how it all goes, the price delta, and other factors) could be to possibly trade-in-and-upgrade (pending your further research), their 4K material. Hey if anything for them, they get even more of your business. I have GOT to think that moiré is a non issue with 4K material. You could ask for a sample if available to know for sure. It's possible that the cost is just not worth it, but it's worth knowing about I guess. You can also ask Seymour for a sample as well, the free small one, just to know. Remember, diagonal tilt it though.
Something that I came across when reading about the moiré effect in the Elite thread, is that you might try zooming way out (small) where the grid gets small enough so to speak, that interference is a non issue. Of course it will suck not to use all of the real estate you paid for, but it's something to tinker with and learn. If feasible, you might pull your projector farther away to help with these experiments.