I think that this will be an excellent screen for many people.
I have yet to receive my sample but based on what others have written, I am optimistic. From Hughman's picture, the HCHP seems grayer than I imagined. Also, both Hughman and millerwill suggest that the 2.4 HP and HCHP are similar in brightness (if Hughman thinks the HCHP is a little bit brighter).
So, a relatively dark gray substrate with a good amount of effective gain must have a really large amount of actual gain. This is so because gray absorbs light. To compensate for the gray substrate's light absorption, the actual gain has to be 2.4 plus whatever amount of light the gray absorbs. So, maybe the actual gain of the screen is 3+ (just a guess).
I wonder how this is accomplished. With an angular reflective screen, an optical coating (or coatings) is applied to the screen. This coating reflects a lot of light but the more it reflects, the narrower the viewing angle becomes and the more visible the coating becomes. But, the HCHP is a retroreflective screen that gets its gain from glass beads. Maybe there are simply more glass beads in the HCHP than in the HCHP. But, maybe it is more than that. The description of the HCHP on Dalite's site says that it has a "highly reflective top surface." This may be another way to describe the glass beads or it may mean that some kind of optical coating has been applied to the screen. So, it could be a hybrid angular reflective/refroreflective screen. Just a theory.
However it works, the large amount of gain restricts the viewing angle more than the HP does. This further restricted viewing angle means that the HCHP will reject more off axis light. No one has yet mentioned any visible texture. That is good and a definite improvement over angular reflective screens (and suggesting that there is no reflective coating applied to the screen).
Both millerwill and Hughman focus on viewing angles. A few points here. If the HCHP is like the stock HP, there may be differences in brightness from seat to seat, but each seat gets uniform brightness over the entire screen. If so, this is a definite improvement over some angular reflective screens in which the image may not be uniform for seats in some locations. Also, even if you can see changes in brightness by doing as millerwill did - leaning left and right in a seat - people generally don't watch things this way (I don't anyway
) So, some difference from seat to seat could be an acceptable compromise IF the light rejection properties of the screen improve image quality overall.
Again, this is all theory because I have not yet seen this screen.