I dont exactly fit your criteria, but I am using a 9' wide 2.35 2.8HP screen where I am getting ~2.1 or so real world gain at my normal center seat with my RS45 mounted 17.5' away. When zoomed out to 9' wide and at ~500 hours on the bulb, I find the image is still plenty bright in low lamp even with my iris at -9.
The lens memory helps out vs doing it manually each time, but it is a bit slow and hardly ever exactly precise. I would say at minimum, 9 times out of 10 I have to manually make small adjustments once the lens memory does its thing. The good news is you only have to adjust the lens shift as zoom and focus always seem to be dead on. Not a huge deal, but it would be nice if the models hitting later this year refined this even more and made it totally accurate.
The side bars for 1.78/85 are not noticeable at all (in my room at least) unless you actually sit there and look for them. Since these are not projected light, I think a big part of how noticeable these are or not depends on how good your room is at killing the reflected light off the screen. If the light coming off your screen gets reflected back to the screen, you will notice them more so proper room treatment will go a long way in keeping these unnoticed from my experience. I have never felt the need for any masking with the side bars like I did with top/bottom bars on my old 1.78 screen with 2.35 movies.
JVC 3D: Been there, done that, bought a DLP