If by "room" you mean a room that's got dark/non-reflective surfaces to minimize light reflected back onto the screen, you're right.
Other than keeping light from bouncing back on the screen from other surfaces in the room, there's nothing special about a "room" as far as projection goes (naturally, I hope we don't need to mention the obvious that the room needs to be dark... as in no skylights letting in light Sunday at noon).
As far as screens go, IMO it's a lot less important to pay $$$ on a screen than some might think. In fact, with today's high-output PJs with good contrast/blacks (like the JVC), you DO NOT WANT a high-gain screen bcs you don't want to hot-spot. Rather, a standard 1.3 gain or even no-gain can look fantastic. CRT machines needed high gain just to make them bright enough to watch, and early digital PJs needed gray screens to elevate the black level. With great-performing modern digital PJs, the best thing that the screen can do is provide an even surface that's smoother than your painted wall.
I prefer Marantz. I have had projectors since my first Advent Video Beam. This is best I have
ever seen....no question. My experience with JVC consumer products is all negative from my JVC camcorder, DVR-SVHS deck etc. I think they make....how you say..."junk. I would never invest $ in one of their products ever again.
Whatever your experiences with these other product lines, the JVC projectors are among the best in terms of quality and are among the VERY best in terms of picture quality.
The RS-series has to be seen to be believed. Not quite as razor-sharp as single-chip DLP, but much better blacks, reds/color, and silky-smooth pictures you can watch for hours without eye strain. Except for absolute black level, they rival the picture of 9" CRT beasts that commanded $60K + just a few short years ago.