just want to share the experience from an experiment I made last night as I'm quite amazed...
I'm a huge 3D fan (when it's done right), however the problem we have with our projectors is that we have a reduction in brightness of about 80% with active glasses (or even more sometimes). Eventhough I have not the biggest screen (93 inch, 1.1 gain), the 3D always was just ok, but far away from the brightness in 2D. (in public cinemas it's even worse, so I can understand people who don't like 3D in a way)
So, luckily I have a Sony HW50 and a Sony HW30 at the same time currently. They both are already quite bright and good 3D projectors with high contrast and good colors, however a little bit of crosstalk in diffcult scenes, but for a SXRD quite good.
So, I decided to make an experiment and to set them up in a double stack active 3D configuration. The problem there is usually to have a good congruence of the overlapping pictures. However, as the lenses of those projectors are quite good (not as good as the JVC, but still), after some careful trying I ended up with a quite good congruence. I only lost a little bit of sharpness, which I compensated with a little 'super-resolution' on my Sony Blu-Ray player. The result in 3D however was outstanding! This was the first time I had the feeling that 3D was really bright as it should be. Some test scenes in certain movies even showed some details which I was never aware before, just because of the high brightness. When the sun was shining in a movie, for the first time it looked like it should and not dim at all. It was so bright, I even could sacrifies some of the brightness to even more reduce crosstalk (with my Monster-vision glasses). I did some calculations: The HW50 has about 1700 lumen in brightest mode and the HW30 about 1300 lumen. Which makes a nice 3000 lumen. If we assume a brightness drop of 80% in 3D, there are still about 600 lumen left behind the glasses which gives me about 25 foot-lamberts:-) Ok, maybe even a bit overkill, but I really like it. Unfortunately I cannot go with a bigger screen at the moment, but it seems to me that such a configuration would be ideal for all people with really big screens who don't want to sacrifies brightness in 3D. Apart from the relatively high costs it seems a good option for me.