Digital BW, The Print

I am currently using the "old" PiezographyBW inks.  I like them and 
have not experienced any problems with my Epson 3000 printer.  
They're not made anymore and therein lies the problem.  My CYAN 
cartridge will run out soon but not my other "colors".  I don't want 
to waste alot of expensive ink so looking for a replacement for the 
CYAN position.  I read on the MIS website that their inks are a 
direct replacement as are the Sundance inks.  Can I just replace a 
single cartridge - will I notice a big difference in print quality?  
Any guidance is appreciated!
Stan