Interesting indeed! Also interesting is that most blu-ray players will output 24p natively; meaning viewers expecting the best level of quality (straight from a blu-ray) will actually be hit most severely by RBE, if they're sensitive! (Presumably, refresh rate can be overridden on some blu-ray players; though I wonder how many users know to do this...)
It would almost make sense for the projector to have a built-in 'RBE-Reducer' mode to rescale all input to 50hz, now that I think about it!
This also explains why I'm picking up rainbows in 3D mode @ 24hz, but not at all in 2D mode @ 50hz. When I listen, it sounds like the color wheel speed does change when setting the projector to 3D mode: do you know what the speeds are in 3D mode? Or if there are any refresh rate settings (compatible with a top/bottom 3D movie) that maximize effective wheel-speed in 3D? My guess would've obviously been 50hz, but unfortunately none of the 3D options seem to be available at all at that refresh rate
(another reason why the timing limits in 3D mode are irritating! )
EDIT: After some experimentation, I've found that if I drop the resolution down to 1440x900 (still 16:9), I get the (sole) refresh rate option of 60hz; which offers me both SBS and Top/Bottom 3D modes in the projector's menu. (Incidentally, this resolution is not on the list of supported timings in the manual). 60hz does improve 3D RBE compared to 1080p@24hz, but it's still not as good as 50hz. (50hz is unavailable at any resolution for the 3D menu to be active, it seems.) This is better - but not great: and I've lost a lot resolution...
It's not permanently mounted yet, but current image size is about 120" from around 3 meters away. And it's a good, clear, bright image indeed: even if I point it straight at the white wall
. In 2D mode, this is unbeatable. The projector's short throw-distance also suits my rather small room very nicely.
That's the funny thing: I don't see 6x being 'officially' claimed anywhere; at least not by BenQ (although I've heard that a BenQ technical manual mentions this somewhere though I haven't seen it myself)... Somehow, this projector is just 'known' for it's faster-than-normal wheel speed. And at 2D/50hz, I'd say they're onto something. Just wish I could find a 3D mode that I could say the same for...