I asked Dennis for some advice - I trusted him with my room design (and he did a terrific job), and one of the posters suggested I asked for a recommendation. I don't know why I didn't think of that myself.
Dennis agreed with some of the earlier posters (that said the JVC would not be bright enough for a room my size). His advice was that for acceptable performance (incl 3d) on my screen / room dimensions ( 1.1 gain / AT screen / 5.6M throw and 3.04 wide screen), I would want at least 2400 lumens. He pointed out only 2 models of projectors in my price range that would do that. Epson was one. Panasonic the other.
After work today I drove down to one of the local stores, and they just happened to have an AE8000 hooked up to a screen about 10% bigger than mine, along with around a 5M throw distance. The demo unit had 500 hours on the bulb, and the 2D performance was pretty good in Cinema I mode, though I thought it could have been brighter. The room was in the basement - so fully blacked out with no windows.
I asked them to put some 3D content on, and as soon as I popped the glasses on, the picture was so dim you wouldn't bother watching it. If that was what I should expect - I think I wouldn't bother at all with 3D.
I don't think the salesmen new much though, because I asked him if the projector would automatically engage a brighter lamp mode in 3D to compensate (I read in the JVC manual that it does this). While his response said yes, he popped up the onscreen menu, and it was clear that it was still in cinema I mode. I asked him to turn it up to Dynamic mode so that I could evaluate the 3D performance in a higher lamp mode, and the difference was night and day. The 3D all of a sudden was watchable - though I'm still not sure I liked it more than my ST50 plasma upstairs. The screen also hadn't been calibrated so I think the Dynamic colors were throwing me off a bit..
A few years ago I had the good fortune to host Joel Silver while he ran a class for professional calibrators, and I have an appreciation for how meticulously they pay attention to calibrating screens. It made me wonder if I kept the projector in one of these high lamp modes and calibrated that mode - whether it might just be the best compromise for my budget, and just life with going through bulbs a bit quicker.
It also lead me to wonder why no one makes a pair of projectors with lens zoom that could be linked together and used for 3D mode with polarized glasses...seems to me having twice the light sources would solve the brightness problem, and some of those lenses are as much cost as another projector.