QTR-Quadtone RIP

hi all:

i downloaded the QuadRIP drivers and am trying to get some decent prints using my 
existing Epson UC inks.  i'm also considering trying the NK7 ink for my fine art printing.  
my image is a straight grey scale image with Gray Gamma 2.2 profile and i'm printing 
using Photoshop CS on a Mac running OS X 10.4.8.  in the print with preview dialog, I set 
the source space to: Document: Gray Gamma 2.2.  the print space is set to Profile: GTR-
Gray Matte Paper, Intent: Preceptual, and use black point compensation.  

in the QuadTone RIP page of the print dialog, i've got Curves 1 & 2 set to UC_EEnhMatte-
cool and the tone blend set to 50/50 (the -black version of the curves seem to print too 
warm).  when i print, i get some nasty posterization that shows pretty harsh transitions 
between gray levels.  this is quite disappointing, since i had high hopes for this.  if there is 
something i'm doing wrong, i hope that someone could point out my mistakes.

i guess my question is, is anyone else seeing this kind of posterization?  i did a nozzle 
check and every color is printing solid lines.  is this posterization a result of the available 
colors in the Epson UC inks?  should i expect superior results with jon cone's NK7 inks?  i 
really want beautiful neutral prints from a selection of fine art papers and keep getting 
something that's too much closer to sepia with the epson inks.

thanks,
scott