Digital BW, The Print

Jack,

I don't know how long you've  played around with these printing
methods, but the right profile is really  key to succesful bw printing.
The big advantage of QTR, IJC/OPM and StudioPrint is that 
they all offer ways for the end user to make or tweak a profile 
to suit their personal preference or equipment.
With IP and others, you have to depend on the company to calibrate
the system for you. In fact, with that in mind, IP offers to make you a custom
profile if you send them  a printed target (for inksets they support).
 That takes the work out of your hands but in turn means 
that you can't tweak things on the fly.

In order to compare RIPs then, you have to make sure that each is
running profiles calibrated and linearized to your particular system.
It's for you to choose if you like to do the profiling or have someone else
at a distant location handle it. Depending on that choice, you go with the
appropriate RIP.  All these RIPs can be made to print nearly 
identical prints. Their differences are far more subtle than your
print comparisons suggest.

My recommendation is to go with printing software that not only
allows you to make your own profiles, but makes the process fast
and fool-proof. Beyond that, you'll need a good understanding
of color management in general, just to make things match across the
whole workflow.

Antonis