Philippe,
I have been working on this as time allows. As best I can tell if you
are happy with the Epson prints, you should be able to get the same
quality with whatever alternative process you should choose. As far as
matching a well made platinum print, no, but how close it can get is
something I havnt established yet.
I know the Fokos method with an imagesetter is considered pretty good
with 450dpi files and excellent at 600dpi, the epson prints stop
improving visually at around 240dpi or so.
What I have found is that the Epson backlight film will give whatever
density range you need, from .4 to 5.5 or so, but it gets pretty
exponential at the high end.
If you persue this please let me know of anything you learn.
Larry