now that I got my 2.4 screen, of course I stuck the 2.8 sample near it (not on it) to compare - it's interesting to say the least.
The 2.8 is pretty much brighter with my setup at every seat in the room. Now, saying that. My room is 19' long, 12.3' wide. I have two couches that seat 3 people each. second couch is on a 6" riser. 7.5' ceilings. Ceiling mounted Projector with 20" drop. 54x96 screen @ 110". Giving details as each room should be different.
There is a better viewing angle with the 2.4. BUT, I need to be up close to screen, like 5' from it, and to the side of it, and at that point, the 2.4 is clearly brighter. But I'll never sit there.
The 2.4 doesn't really have a sheen or paisley look to it in bright scenes with normal watching. But if I take a flashlight, lamp etc and observe from inches away, there is a noticeable reflective type pattern to it, almost like marks from rollers. Again, it's something you can't see unless inches away from it. I can however see a paisley type effect in bright scenes with my 2.8 sample. Barely.
Coming from an Angular screen. The M2500 with a +2 gain. I am surprised at the amount of light the 2.4 catches from other sources in the room. Windows, I have night lights near the floor, if I keep my pot lights low etc, you can clearly see the screen effected by it. It's got kind of a cool glow effect when not using the screen though as it just sits there picking up lights in the house.
My M2500, old version was clearly better at black levels. It's a no contest, painfully obvious scenario. I am now curious to see the new m2500 on it and will try it later on.
Now the good. Just talking about the 2.4 now. I see no hot spotting, no real color shifting as I walk around room. There is a slight brightness shift as you get to the sweet spot, but honestly only "we" would notice. Average users are just going to sit down and say whoa! regardless of where they sit. Its actually quite amazing how even the gain is across the screen. After looking at the samples you would think there would be a larger more noticeable difference but there isn't. Blacks are a touch, and I mean very minor touch better then the 2.8 that I can see.
For a long and narrow room like mine, I still say the 2.8 is better. In fact, I think I was happier with the old m2500 despite it's minor flaws over the 2.4. Too bad you can't get either anymore. I have already contacted Da-Lite with my "opinion" on the 2.4. It should have been a seperate product, not a replacement.
For a Wide room, the 2.4 may work out better for you.