Digital BW, The Print

I am planning to set up an Epson 7500 printer for quadtone printing. 
The printer is hopelessly clogged in the first two nozzles so I need 
software that will allow me to reassign ink colors and switch off the 
first two nozzles. I prefer to work on a Mac but also have a PC if 
needed.

I have lots of experience with the original piezography software and 
inks (now Sundance / R9) used with Epson 1160's and 3000 printers and 
have had fantastic results.

I am considering StudioPrint or OpenPrintMaker (IJC/OPM) because both 
will allow me to reassign ink nozzles (I dont know if any other RIPs 
will do this also).

Does OPM yield as good results as the others?

The problem is that I have heard that neither of these would give me 
the "grainless" dotless prints I have been getting with the R9 
(Sundance) software. Is it true that the dotlessness in OPM only 
applies to the highlights? 

I wonder if anyone has had the opportunity to compare R9 to 
OpenPrintmaker and StudioPrint in terms of overall quality, tonal 
range and dotlessness. (and what about Cone software?)

Any light that you can shed on the subject would be greatly 
appreciated.

Thanks,

Bob