As we approach the maximum vertical lens shift does the image become less sharp? I have never seen any testing on this aspect of projectors. That is one of the big problems that I am having since I am about to purchase my first projector. Maybe the JVC looks great when it is using zero lens shift but maybe even with a minimal amount of lens shift it starts to look like a $999 projector? I doubt this is the case but it is difficult to understand how one projector would perform vs another in our specific room. Are you aware of any testing or resources that discuss this?
In theory the less lens shift you use the sharper the image. Same goes for using long throw vs short throw. This is because the center of the lens is usually considered the best spot to shoot the image through. This is because the center of the lens may be the best polished and have the fewest imperfections. Now if a lens is just as polished up to the edges as it is in the center, you may not be able to tell the difference in a side by side test. You certainly are not going to see the difference between the two if you do not have them two side by side. Also with extreme lens shift you may get more CA.
You place a JVC and a $999 projector in a good room and shoot onto a decent screen and you will not have any problem picking out the JVC no matter how much lens shift you use. Still not a fair fight. The JVC will blow the other projector away with most material.