One more time: I may refer to the black level performance of the HD20 as entry level by today's 1080p standards, but it is comparable to most far more expensive projectors of just a few years ago.
Even with that in mind, for those of us who really appreciate the deep blacks of the more expensive "ultra-high contrast" 1080p projectors, it's a significant and important difference. The real question is whether or not the black level performance of a projector like the Epson worth an extra $1500 plus to you. The Epson, by comparison, has no advantage in terms of handling of skin tones, and can't match the shadow detail of the Optoma HD20!
You'll find this next image in a number of reviews. It is a logo at the beginning of Batman Begins. With projectors with blacker blacks, I have to overexpose the image so much (to bring up, the blacks to a just visible gray), that the logo turns almost white instead of blue. Here, however you can still see most of the blue, as I barely had to overexpose the shot to get those grays.