the MMV responds well to 14 bit. I use NRPN with 1450 steps, and when I slowly move an encoder, I cannot hear any quantisation. But I can be mistaken, there are synths that I control with 7 bit and it is difficult to hear quantisation. Anyway, I found it advantageous to control the MMV with 14 bit.
The GUI does show steps when you rotate a knob, but this is just a graphic representation that does not have to correspond to the sound itself.