Based on my experience GMG Color server with Ink Optimizer is the best solutiond around there. Let me know if you may need any help from us, or get some info from thePrintLabs.
We have tested ink savings on web offset between 25% and 35%, and between 20% and 25% on lithographic presses. There are several ink saving transformation profiles embedded, and you can play around with different tac levels to meet your quality requirements and obtain the best result on your press.
Stefano Garavelli
founder of theprintlabs.com