Digital BW, The Print

Joost,

Since you are already using QTR, that makes the most sense at least to 
start. For a purely monochrome or toned monochrome inkset you may want 
to move to the Bowhaus RIP
http://www.bowhaus.com/services/IJCOPMmain.php4

The curve creation was more friendly the last time I compared it to 
QTR, but that has been more than a year ago, so may not apply now. Also 
not sure how the price compares to something like StudioPrint or the 
Evolution RIP.