Upgrade the projector or projector screen?

Hello Everyone!
 My Current setup: 
Epson 5030ub + Screen Innovations series 3 - solar white (1.3 gain) 100 inch diagonal.

I sit about 8 feet away from the screen and my HT setup is totally dark with grey walls. 

My goal is to upgrade the picture quality and I want to stay under or around $5k. 

My QUESTION: Should I upgrade to a Stewart Filmscreen StudioTek130 screen OR upgrade my Projector to a JVC DLA x790r or similar? 

What will make the biggest positive impact? 
So screen quality does not matter as much as claimed by a couple of resellers of screens I spoke with !?

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.

My 13 year old son said he could see the pixels when we had the Epson 5030, but the picture is noticeably sharper with the 6040.
@ricred1 thanks for your feedback! To my eyes 6040 is slightly better but not by a huge margin. 

I'll be switching to a JVC x790r. Let me know if anyone is interested in an Epson 5030ub. It has about 188 hours comes with extra bulb (new) box manual remote and 3d glasses 
Last question:
Going to a JVC x790r from Epson 5030ub. Is that a significant of an upgrade?