Well its all great if you got a good sample, no doubt, but its not fun to get 2 samples with 75% contrast drop in the corners, and dE 15 in color uniformity error with fully closed iris.
You can try setting the iris to -15 on your N7 and put a white test pattern up, ill bet the corners get quite yellow. You might not have a problem with that as you might run it much more open where its not a problem, but people with 90" screen will.
Also had a dust blop on the blue panel on one of them right out of the vox, along with multiple stuck pixels.
No doubt that's extremely unlucky getting 2 projectors that bad, but it happens, even the NZ series goes back with dust blops and defects.
No light path on any projector is sealed, not sure why anybody thinks so.
As you have both the N7 and NZ8 it would be interesting to see the paper test on both your samples.
Here is a N/ example, the dust problem is biggest on hanging units, not so much on standing units
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