LCOS seems the most 'plasma like' imo.
I've very happy with the jvc x35 compared to my Samsung f8500. in fact, I'd give the nod to the jvc in pretty much every category, including black levels. whatever the plasma does better, it's only barely better and not very noticeable to me.
while I agree, an 'optimal room' is a bonus, I would not say it's a requirement by any means. if you can keep the lights off, you're still going to experience that incredible on/off contrast and impressive fade to black. bright walls/ceiling will not affect black levels much, but it will affect ansi contrast with mixed scenes. fortunately, when there's something bright on screen(bright enough to light up your walls and reflect light back onto the screen), then above black black levels tend to still look good anyway.
basically, as long as the lights are off, you're still going to get great performance. but treating the walls/ceiling will add even more performance, pushing it BEYOND plasma quality imo.
watching with lights on is a whole different story, and imo, is more about the screen. a white screen simply doesn't show black well unless no light is hitting the screen. if you have lights on it will wash out the image big time. and it doesn't take that much light(if it's hitting the screen) to be noticeable. the light coming off my cell phone is enough if pointed towards the screen. a small led flashlight can completely 'erase' the image on screen. if you really intend to use a projector in a room with lights on(and hitting the screen) you need to figure on something like the black diamond, or similar style screens. they are not cheap.
the other way around this is to aim your lighting, and not let it 'flood' the room and hit the screen. I can turn my potlights over my seating up pretty bright before it affects the image on screen. but the lights that hit the screen need to be turned completely off for it to look any good.