For a couple of hundreds dollars more they could have gone with a 1280X720P projector. My guess is that they wanted to keep those screens at 4:3 for those sizes.
I'm not sure about the E6's intended image ratio but GSA was designed to be 16:9. I mentioned in a different thread that running GSA in 4:3 will cut off the sides. Not sure if it would be the same with E6.
If the E6 was created for 16:9. I would hope that their Signature and Premium simulators uses 16:9 1080p projectors. I sent Trugolf a question concerning this. Will post when I get an answer.