an MFDB is mirrorless. I can put my back on Hasselblad V or Hasselblad Flexbody. But I think that LV and EVF are missing components. Latest backs have some LV capability.
That is key. High quality Live View is a huge asset. A high quality EVF would be the icing on the cake. Even the low quality Live View in the Phase One IQ backs is a BIG help.