I understand your point (I really do) but as I indicated the noise reduction in my post is present I don't see your point of a "hidden" variable as all variables are on the table. I also feel that the scanner and scanning software are a HUGE variable, much larger than NN (esp when you consider the range of scanners made today). I also feel that using NN with a careful approach there really is a big difference in grain from film to film...using the default NN is not my technique as it kills (IMHO) the look of film. I hope that my posts on FR get others, as you have indicated you have, to try these "solutions" for themselves (which is always best) and see if it works for them and their needs. I never personally trust anything I see on my monitor from the web site as Gospel- but it does give one an idea and something to perhaps consider and try. Great conversation!
Best-
Stephen Schaub
To the extent possible we should eliminate, IMO, as many variables as possible in comparing grain and sharpness in films. I agree that scanners, and even scanning technique, are big variables in the perception of sharpness and grain. But why add another variable, i.e. software that impacts grain, to the equation.?
For what it is worth, I agree with Don (and by extension Marcus Aurelius) in that you should take Noise Ninja, or any grain reduction software, out of the equation. Then we only have the issues of film, developer and scanner to consider. That is complicated enough in itself.
Consider it a matter of first principles. If you add fourth principles over first, second and third principles the result may be chaos in understanding. The point that you make then becomes relevant only for your specific work flow.
Sandy King