I understand that's the actual, original title, but it is so semantically meaningless. GFX is a "Mirrorless Camera" (with a large sensor). So of course it "performs like a mirrorless".

I get what they're trying to say ("This is not your daddy's medium-frame"), but the notion that these are somehow qualities intrinsic in a "Mirrorless" designation irks me. (Certain) DLSRs were fast, small, portable, effective and efficient long before mirrorless.

As well, the notion that GFX isn't a "Mirrorless", or that "Mirrorless" implies a particular sensor size (such as m4/3rds or similar) is again erronenous.

Medium format was expensive, unwieldy and slow due to artificial market segmentation, limited competition, and essentially being at the far *-phile end of the price/feature curve.

Fuji is a new entry and an underdog competitor, which is what drives most of the attractive features, not just the mirrorless part.