Few simple points about comparing projectors:
Comparing two projectors involves 3 things:
and finally, 3) More Calibration...
OK, I know some attributes of the picture you can compare without a perfect calibration, that is somewhat true. However, let me share my experiences and frustrations in just how hard it is to properly compare two different projectors, especially from two different techs near the same price range. Believe me I am not picking on anyone, I've been there done that, I've made the mistakes myself to later realize how important spending a LOT of time on a calibration is when comparing two projectors, I've even had to reverse my own findings and call myself stupid. Comparing two projectors takes a lot of practice and it is not an easy thing to do.
Now comparing two projectors where the differences are night and day (like a $5000 JVC vs. a $500 Acer), that's a lot simpler than comparing two projectors to where the differences are much more minor, as is in this case. So I am not belittling anyone's comparison, but this comparison is extremely difficult to do properly and really needs to be done over many hours of calibration and viewing. I realize this is something most of you do not have the luxury or time to do, so I'll give some leeway here. For the fence sitters, I wouldn't judge these projectors too much from some of these comparisons, I would investigate as much as possible of course.
For instance when it comes to shadow detail, shadow detail is primarily a function of native contrast almost exclusively, a projector with a higher native contrast calibrated correctly should have the better shadow detail. However, projectors that are this close in native contrast should have for the most part imperceptible differences in shadow detail after calibration, if they don't, then your calibration is off. The one exception to this is if there are some Noise Reduction algorithms or other image processing things taking place in the image reducing the shadow detail, but this is not usually the case. Hence, spotting a significant difference in shadow detail between these two projectors is almost certainly an uneven gamma curve between the two. Not saying you cannot spot some tiny difference, that is possible, but it shouldn't be very large.
Remembering the image and trying to remember what you saw is very difficult when going back and forth, and in order to compare two projectors in a split screen condition will cause you to lose ANSI contrast, so you have to do some pretty fancy things to solve this problem. Hence, there are times a split screen will be needed, and there are times each projector needs to be watched independently.
Sharpness controls, you need to get the artificial sharpness matched up between the two to make sure the noise in the image is similar between the two devices. The different levels of sharpness can make one projector look better on some content, but worse on others.
Getting the brightness, contrast, and the gamma curve EXACTLY the same between two projectors when comparing is an absolute must. You cannot compare two projectors with different gamma curves and claim one has better POP, it is like trying to determine the sub-species of a black frog in the forest in the middle of the night.
Of course the most obvious is getting the color accurate on both projectors. The room conditions must also be setup very well.
Finally, the content you use is important to compare with, you need to pick content that favors each projector and not just one or the other, so that you truly get a feel of a projector's strengths and weaknesses. Any comparison that finds one projector to be superior in almost all conditions is almost surely invalid when comparing two projectors that are at the same price range. Sure occasionally one projector could take the cake in all categories, but it is very rare. I suspect the Epson probably has the better OTB calibration, which is why some of these findings are so different.