Cross-posting my projector buying experience in appropriate threads...
I purchased the Epson HC4010, installed it, used it for a few days, and the lack of contrast because of high black levels bothered me. I returned it and purchased the HC5040UB, which is now basically the same price as the 4010 because of the sale and free lamp - I think Epson plans to replace the 5040 with a new model soon.
I installed the 5040UB and immediately noticed the lower black levels in almost every scene, which gave the picture greater contrast and looks far better.
When projectorcentral compares the two projectors and talks about black levels, they basically say the difference is not small. Here is their conclusion: "The HC5040 has better contrast and, especially, lower black levels that far exceed the capabilities of the HC4010, but which are really only brought to bear on very dark scenes, and in dark-room theater viewing. On most bright or mixed material, or in even moderate ambient light, both projectors are close in contrast performance."
However, I don't have a light-controlled room (yet) and I have a white ceiling (for now) and I have to say, I immediately noticed the higher contrast in just about every scene except where the entire image is bright. Think of it like upgrading a TV half-way from LCD to OLED. In this price range, especially with 5040 sale prices, the 5040UB is a no-brainer.