It was late at night and I made a joke. Obviously, every projector has weaknesses and has traits that annoy owners. Why can't they do that, why didn't they do that? Of course changing anything costs money.
As an avid reader of projector threads, I get a little jaded. I do think you have a right to be annoyed, I just think in the reality of things it would be no more than a minor annoyance at most for many. Please do not be offended. I was just goofing a bit with you. I do that.
Please forgive me.
Now optimum set up. Every projector trades brightness vs on/off based on throw distance ratio. Place it closer, you get more ANSI lumens out but less on/off. Place it farther away and you gain on off and lose some ANSI lumens. The functions are a log function and putting things in the middle gives you probably close to the worst in any direction. From end to end, the fall off in either might be around 30% with most of the fall off occuring rapidly as one moves from an extreme. For maximum of either, one needs mounting close to an extreme. One has to chose their poison. What do you want? This will involve screen size and gain. What's the minimum of either you will accept? This is best discussed with a call as we can go into everything and you can make relevant choices, something you must do, not the advisor.
As to lens shift, the more range a manufacturer provides the greater the possible optical deterioration in image quality available. The smaller the lens diameter the worse things can get. Just remember for optimum optical performance, geometry and focus, and lack of chromatic aberrations, a lens will perform best if the chip imagre coming out of the optical block is centered in the lens. The bigger the lens, the bigger the center area is and the more you can shift away from that without deterioration. Now do not be afraid to use lens shift if you need it, just try to stay away from the extremes. Even at close to an extreme, performance over most of the screen will still be good but not as good as possible. If you want to discuss, just give me a call.
The problem described does not appear to be a dust blob. Some defect in the optical block, probably a panel defect, Just relax and wait until Monday to call your dealer, I am sure they will promptly resolve things for you.