I have a 138" 16:9 EN4K screen. Wall to wall. Check out my pics.
There is no comparison for the level of immersion with the speakers behind the screen, nothing to distract up front.
I came from a 106" DaLite JKP Affinity screen (Probably on par with the Stewart) with speakers behind an AT black screen wall, but the wall to wall screen is just awesome.
My JKP screen was a 0.6 gain gray screen, so the EN4K is a little *brighter" than the solid screen.
Picture quality is outstanding on the EN4K. Unless you are standing one foot from it, you can't tell it's AT.
I upgraded from an old 106" DaLite screen to the 106" JKP, and it was great, but you will always wonder what difference the AT wall to wall will make and you will end up swapping out later anyway. Just do it.