[thxbb12]

I bet that a MFT + 27.5mm f0.6 lens does not have the small form factor of my Canon EOS 6D + 55mm f1.2. 

 

Obviously not, but you're missing the point. MFT has unique camera + lens combos. For instance:

• Oly 9-18 f3.5-5.6 : tiny UWA. Good luck finding something that small with FF. Before your bring up the DOF equivalency: sure it's only equiv. to a f7-11.2 lens. However, the aperture in this case doesn't matter a bit. If there was an equivalent FF lens then I'd definitely be interested.
  
• Oly 45 f1.8: tiny portrait lens. Sure, it's merely equivalent to a f3.6 FF lens. However: where can I find such a compact FF portrait lens? Doesn't exist. Same with the Oly 75 f1.8, etc.
  
• Pany 45-150 f3.5-5.6: tiny 300mm equiv zoom. Again, the aperture doesn't matter.
  
• etc.
  

There are tons of examples like this in both MFT and Fuji-X systems. Now, it's probably possible to make FF equivalent lenses around similar sizes. However, nobody manufactures such lenses and it looks like it's not gonna change any time soon... Hence, my sentence: 

 

Today, only 2 systems fulfill these requirements: Fuji and MFT