P800 Change from color to Piezo Pro BW

I am changing a P800 from Epson color inks to the Piezo Pro BW ink set. My nozzle checks print out perfectly (no clogs). Is it recommended to use the Piezo Flush before I switch to BW inks? Will the cost of doing this save me money on the BW inks? Or will I loose just as much BW ink after the piezo flush as I will after the Epson color inks? Is there any other advantage to flushing with Piezo Flush at this point? Thanks.