I will expand upon the question with sample images, of a coregistered slave from a coastal area using a small area for demonstration:
I band image, no data value is active:
I band image, no data value is inactive.
Band maths of the previous two images, where I substract first from the second:
Comparing the two images in it is clear there is a difference, as the first one has more “no data value” pixels.
Upon closer look with the difference image, I get 4 pixel “spots” all over the image, where the results differ due to bilinear interpolation. If I use another interpolation method, the results differ even more(how many pixels used for interpolation).
I feel that the results cannot be correct if I leave the “No Data Value Used” as active, however I would like someone to confirm this.