We switched to MSS on our JV33 and had an issue with the black. So we kept the ss21 Black, and used MSS M,C,Y. Then we switched to JVV M,C,Y bulk and were unhappy with the Magenta. So now our silly arrangement is ss21 Black, MSS Magenta, and JVV C & Y bulk. However, with the MSS, the tab that pops out to let the printer know it's out of ink, overshoots the sensor and the printer doesn't read the cartridge as empty and the ink can drop out.