see link: http://mantis.image-systems.biz/view.php?id=2693
this is to let you know that the .ini file tweak you asked me to try solves my "grey print" issue.
In case other users may need it, with my SONY FimStation UP-DF550 the required settings are:
MinDensity=0
MaxDensity=300
it's also necessary to change the Border density value to 300 in the DICOM print settings of iq-VIEW in order to avoid a "grey border" film.
thank you very much for feedback.