QTR-Quadtone RIP

Actually this is possible on the V850. The "holder" for films all have these notches to raise or lower the emulsion vs the glass. I don't know if it helps but I made some test nd, yes, there is a big difference.

Yes.  I have the V800, which works the same way. Epson finally realized that their manufacturing tolerances and quality control were not fine enough not to require minor adjustment by at least some end-users.

I used to have a 4870, and bought a much-improved, 3rd party 120 holder.  I can't think of the name right now, but I corresponded with the designer, asking whether the Epson might not be improved by replacing the glass platten with one that had an opening (cut out) so that there was no glass at all between the lens and the film being scanned.  My recollection is that he said he had tried it but could see no improvement.

Myron