Upgrade the projector for sure! The two screens you mentioned are pretty much almost the exact same thing. Both white with 1.3 gain. Both are very nice screens. You are not going to get any difference with a new screen unless you drastically change the material (i.e. grey/black toned or super high gain). Since you have a completely dark room, you're best result will actually be with the standard 1.3 gain screen. Put your money into a much better projector.
You can also look at Sony projectors. The JVC DLA projectors are noted to have very excellent black level and a film-like quality. The Sony projectors are excellent as they make the image "pop" a lot more. The Sony is a little bit more exciting but does not do as good in the lower blacks (shadow detail).
You can also look into a Lumagen Radiance video processor and then do a calibration.
No doubt about it, upgrade the projector. For $5k you will be able to buy a used Sony 4k projector. I recently went from HD (Sony VPL-HW65ES ) to UHD/4k (Sony VPL-VW665ES). The difference in resolution and general image quality is staggering.
@auxinput: thanks for the advice. SI and Stewart are both 1.3 gain however I've seen Stewart studiotek screen and it is way smoother than my SI. That's why I wanted to know if swapping screens would make a big difference. Ive also heard from 2 different resellers that upgrading screen is more important. Have you ever A B'd screens with same projector?
I actually have the Stewart Filmscreen StudioTek 130. It has a very very slight texture to the surface of the material. If your Screen Innovations surface is perfectly smooth, I can sort of see how you would think the Stewart "looks" smoother on video. I think the texture on the surface acts to break-up the separation between pixels - as the LCD pixels do not have a great fill factor. If you look closer, you might get a "screen door" affect where you can see the pixel grid. If you wanted to smooth out the effect of your current Epson LCD, the Stewart -MIGHT- help fix some of that pixelization roughness. I don’t know for sure. You can also solve for this by very slightly de-focusing the image so that the pixels sort of flow into each other.
The JVC DLA and Sony LCOS panels have a much better fill factor - you will get less of the screen door effect. I have an older Sony VW95ES 1080p that I just love. To this day, I have not had any urge to replace that projector. Though, it does have a color calibration using Lumagen Radiance processor. If you’re not worried about 4K output, Curt Palme website is selling the Radiance 2020 for $1399.
I think your screen is very good and your projector is too. If you really want to upgrade now, then the projector will make the biggest impact. if you had room lighting or a very crappy screen now, i can see how a better screen would make sense. personally Id wait a year to make a bigger jump but either the sony or the jvc 4k projectors will be a decent upgrade if your sources are hdr.
Why would you buy a white screen for a dark room? Your blacks are only as black as the screen, I would have gone with a 0.7gain or similar if my projector could handle that. It’d be like going from LED to OLED.
That said, not sure you should upgrade that over the projector, though the Epson is good.
Maybe he wants white screen vs gray.. That way the whites are white and the colors are vivid. Grey is gonna dull it down a bit on colors. Grey is good if room has ambient light, but you get duller colors and off whites.
my jvc dla 4k upshift projector doesnt have any problems doing black onea 1.1 gain white screen by draper in a dark room.
In today reality, when the techs are getting old too quickly, I would suggest you sell the current one and buy something newer, for example, BenQ MW535A, it's well represented in this overview, but other options are also viable, at your preferences!