We just discussed this in talkemount forum also as Sony f4 lenses pretty much are matching the Canon f4 lenses. I am still keeping my smallish $160 Sigma 24-60 2.8 EF zoom which is nearly same size as these zooms with nearly zero distortion, but it is mf w/ Sony and don't know how it will do w/ high MP and sometimes I prefer to have the IS then the faster 2.8 esp when you stop down... Of course Zeiss will give better colors and contrast.
I added up the other f2.8 mirrorless zooms to your comparison, as most of them are not that small unless you go to high distortion pancake slow zooms (no Fuji 2.8 zooms available yet, so only kit lens and m43 2.8 zooms comes w/ 6-6.5% distortion correction)... I added up 24MP Sony A77 w/ 16-50 also as unique photo had one selling for $1100 as a combo which is cheaper then all these fast mirrorless zooms, so I can see why the mirrorless sales are struggling (at least we still have some weight savings w/ mirrorless as you said):
Compact Camera Meter
Zeiss zoom is not the perfect lens for A7(R) like the FE primes esp w/ Sony QC, but it is good enough walk around zoom that made Tim Ashley to sell his perfect EM1+12-40 and his comment:
Sony 24-70 F4 Lens