Screen Door Effect and Rainbows
The visibility of pixels (and potential resulting Screen Door Effect) is an important issue for most viewers, and it is a far bigger issue with these lower resolution projectors, since their pixels are much larger than the HD 1280x720 projectors. The BenQ W100 uses DLP technology, which has the benefit of having less visible pixels than LCD projectors, and that may explain why there seem to be less and less low resolution LCD based projectors on the market.
Sidenote: We recently reviewed the "all-in-one" Epson MovieMate projector (with built in sound, and DVD player). The Epson is the same resolution as the BenQ, but is LCD. The pixels there were so much more visible that it was the primary cause of internal debate as to whether that otherwise very impressive projector would receive a Hot Product Award. In that case, the Epson received the award, as I considered an all-in-one, even less "purist" oriented, and that buyers would be even less critical, notably since most buyers of entry level projectors are making their first move from traditional much poorer quality conventional TV's and lower resolution Big Screen TVs.
But, getting back to the W100 home theater projector, you still need to sit significantly further back than with a higher resolution projector before the pixel structure dimminishes to the point where it is barely or not detectable.
Shown below is our closeup of text that we use in many reviews. You can see the pixel structure here, and if you wish look up the same image on most projectors reviewed in the last 6 months or so.
Optimum viewing distance to keep the pixel visibility to a minimum (such as in white text in movie credits, or very slightly visible on large bright (stationary) areas of scenes is a little less than 2 times screen width. Therefore, if you have a 106" diagonal screen (92" wide), that would be less than 184" wich is about 15 feet. I believe most people looking for an entry level projector will not be that critical, and will find viewing comfortable (although pixels will be visible) in this regard sitting as close as about 1.6 x screen width or, for the 106" screen - just over 12 feet back. This is an issue of personal preference. The only cure is to spend more money for a projector of higher resolution.
As to screen door effect, as the name implies, it gives you the impression of viewing through a screen door. The important point, is that with some content, where there is fine detail such as the grass on a football field, the pixel structure mixed with the fine content may create a patterning that noticeably distorts the image. The smooth grass detail might start looking more like clumps of poorly focused grass. Annoying SDE is the result of the pixel structure mixed with particular content that tends to magnify the distortion. BTW, my own feelings are that SDE is definitely more of a problem with lower resolution source material than high. Translated, you are more likely to be bothered by it watching a regular TV signal on the W100, than watching a DVD or a HDTV signal. So the good news is, it should be less of an issue, as more and more of our content goes to higher definition.