After following this thread for a year, I finally got the projector last week. I also have a Mitsubishi HC3800 and an Acer H5360BD, and I'd like to give my subjective comparisons for anyone familiar with either of those projectors and are thinking about the W1070.
I have a 90" 2.5 gain screen. Both my HC3800 and H5360BD have over 2000 hours, so I'm trying to keep in mind that I'm comparing middle aged lamps to a fresh one in the W1070. All of these projectors I run in eco mode (not Smart Eco). My W1070 has firmware 1.07.
W1070 vs HC3800
The W1070 is much brighter and much sharper. I'm surprised how much sharper it is despite them both being 1080p DLP projectors. With ambient light, the W1070 is of course much better.
In a darkened room, I think the HC3800 is a little better thanks to its good ANSI contrast. Without an ND filter on the W1070 however it's a little hard to compare contrast in this environment, as the difference in brightness between the two is so obvious. The HC3800 is a little dimmer than I would like at this point, but otherwise gives a nice rich image. The W1070 is very bright, but not too bright for my tastes even in the dark. Black levels seem to be the same, accounting for brightness as best I can. Not great, but not bad in either. I should note that I had to turn brightness down to 46 on my W1070 to reach its native black level. In any case, the W1070 won't be replacing my HC3800.
W1070 vs H5360BD
Brightness seems comparable in both 2D and 3D. The W1070 looks a little brighter in both modes but I think this is likely due to the aging bulb in my H5360BD. 2D image quality seems more natural in the W1070 thanks to the RGBRGB color wheel vs the H5360BD's RGBCMY. The main reason I got the W1070 was for 3D Blu-rays, and of course it's better thanks to native 1080p (I watched Prometheus, The Hobbit, and Pacific Rim). I assume the 144hz mode is also improving the image, but I can't say I can specifically pick it out. 3D Blu-rays just overall look a lot better.
I also play a lot of PC games in 720p 3D (Nvidia) and I was a little concerned about how it would look upscaled to 1080p vs viewed on a native 720p projector. However, I think it looks slightly better upscaled on the W1070 thanks to being smoother and having a less obvious pixel structure. Once I get up the nerve to upgrade the firmware to 1.08 I'll be able to use TriDef at 1080p SBS 60fps, which will allow me to play some games in 3D that don't work well with Nvidia 3D.
So unlike with the HC3800, I think the W1070 is a straightforward upgrade vs the H5360BD.
One comparison I didn't make above is fan noise. That was one of my biggest concerns before buying the W1070. While it is louder than the other two projectors, in practice I don't notice it, so it's a non-issue for me. All 3 projectors are/were shelf mounted about two feet behind my head.