I can only perhaps help in general terms. I have owned several types of HC screens including models from Da-Lite and now Draper and I think they work great. I have not owned Elitech but if searches show they are a quality company, I think you will be fine. I have my projectors (old Optoma HD66 and now a - "new" Epson 3010) sitting on a dining room table during football season and projecting onto a pull down screen. The room is kind of dark naturally though it has openings galore. I have a blackout drapes on the window facing the screen and which faces South, and am very pleased with the picture in some ambient light. (I also have an entry way from the old dining room, window midway up stairs behind screen, small window at bottom of stairs behind screen and door entry way from just behind side of screen. Believe it or not this was still the best place in our house for the screen! The screen backs to the stairs and is in the darkest portion of the room.)
In the past I have gone all out to make it darker but with the more powerful projectors like what you will have, it isn't necessary. I even use mine with higher gain screens and am happy. I am not super critical. But I do own Panasonic plasmas because I love their pictures so I am not totally clueless either
FWIW - the screens I have used the longest.
Da-Lite HC and high gain 2.7
Draper Contrast Radiant also 2.7