QTR-Quadtone RIP

I've got an Epson 3000 with Selenium-toned QT inkset, and am having trouble getting decent 
results.
I've already set up Epson Photo Quality Inkjet Paper (which I use for drafts in A4 and A3 sizes) 
successfully, but am stuck on getting Hahnemuhle Photo Rag 308 gsm working right.

At times I've ended up with very grainy results, which playing with GRAY_OVERLAP seems to 
help.  But no matter what I do I always seem to get L* values that don't continually get darker 
(especially at the dark end).  I've been reducing and reducing the ink limits (although this 
makes the grain more of an issue) but haven't found the right point yet.  It's a slow process, 
as the prints take quite a while to dry down (not that they seem wet, but the L* values keep 
changing).

If anyone has QTR files for the QuadTone inks on Photo Rag they'd be prepared to share 
(even for different printers: it should give me some hints) I'd be very grateful!
__
David Burren