I am grateful for this thread. I went to redo my grayscale on my RS40 and I wound up setting a couple of my offsets to a positive number in order to achieve a better grayscale. When I was done I watched a few movies and didn't know if it was the blu-ray transfers or what but my black level was raised. I then read a review of one of the blu-rays I watched and the review said it had excellent black levels. I found this thread and saw that raising offsets to a positive number can raise black levels. I then redid grayscale and left offsets at zero or below and now my black is back to excellent.
So thanks again for the tips in this thread,
WTB: DPI Cine LED 1000 projector