Sorry, I'm not sure what you are referring to exactly when you say °This is what they say", since I wrote such long, convoluted post haha. But I think I know what you mean, I have read that contrast is the single biggest factor in how people judge movie picture quality on average.
As to those posts, yes, those are indeed the ones I was thinking of when I mentioned ANSI vs ON/OFF:
"Black screen 0IRE (black), on /off (black white) contrast is at least 2 times higher with the 3800/7100 (appr. 475:1 vs 1.200:1), used equipment HCFR, Spyder4.
But with more bright content in the pictures the Ansi contrast performance gets more and more simular. Also the black level is appr. equal (also in live view)."
I was glad to see Gregory's review confirm not only that there was a measurable difference in contrast but also that there was a notable visible difference, even if the degree of difference might be more subjective and dependent on the screen and room.
Yes, it definitely depends on content, with my current projector some type of shows that are mostly bright scenes, like travel or documentary shows, look great, while shows or movies with a lot of night scenes really show the lack of shadow detail and the grey black floor.
It's somewhat subjective and up to taste as well, some people claim not to care about one or more of: shadow detail, black levels, black floor, dark scene performance, etc.
I can't understand it because to me contrast and "inky" blacks are somehow the most pleasing and engrossing aspects of the image, and I care about them more than other characteristics such as sharpness or color accuracy (within reason).
If I were to buy one of these projectors, I couldn't resist getting the 3800/7100 over the more economical model for that reason, and I'd be willing to pay the extra, assuming there wasn't something better at the same price.