We can assume the Benq produces a very nice image, based on reviewers and user reports, probably every bit equal to the Mits hc4000, perhaps even slightly above in some respects, perhaps slightly below in others.
My best guess without seeing the two projectors side-by-side, remember a best guess, is that the Benq w1100 will beat the Mits hc4000 for overall sharpness including sharpness uniformity across the entire screen, this could be a TINY TINY advantage over the Mits for some video games, but for TV or movies it shouldn't matter. Again, just a guess until more reviewers confirm it.
As far as color, it is impossible to say without seeing the two side-by-side, both the Mits and Benq's are so close in native contrast that the colors after calibration should be very very close, should be practically identical. Bit rate schemes and all that is more marketing stuff than reality, color accuracy is more important as well as primary color and gray scale calibration accuracy.
My best guess is these projectors are VERY VERY similar in overall PQ, probably most people could not tell the difference in most situations. The Mits hc4000 may have slightly better black levels, but that is not confirmed yet, and we know the Benq w1200 is supposed to have even better black levels than the Benq w1100.
The Benq does kill the Mits at one thing, and that is brightness, both best mode and overall. With the Benq, a very nice GIANT image is easily obtainable on a VERY large screen. The Mits hits limitations at over 130" to 140", the Benq can be pushed even farther.
I wish I could compare these projectors, and maybe I will, but was hoping someone else that has done many comparisons would save me the trouble. You really need both projectors side-by-side to do a proper comparions. Even as much as I have viewed projectors and compared, I would be hesistant to trust my memory alone, especially in a comparison that I expect to come out almost too close to call.
I agree about review sites not being the ultimate source of information, they have led me astray one too many times. The best sites I have found are Cine4home and projectorreviews.com, with some caveats. Art @ PJ Reviews is a very very good reviewer, one of the absolute best, but he tends to overrate black levels, which distorts any findings. That said, he sometimes does go into bright scene pop and often goes into skin tones too, but I don't trust the calibrations they do over there enough to be valid. You can trust one thing he does do, and that is black level comparisons. I'm not saying his black level comparions are perfect, no-ones are, but what I am saying is for the most part I have come to the same black level conclusions he has, which re-affirms my trust in this aspect of his testing.
I will wait to see what he says about black levels.
One thing is for certain, you are VERY unlikely to EVER beat the image of the Benq w1100 for under $1000
(I think almost guaranteed it will be the best at this price).