The sensor size is irrelevant because the Gx7 just performs so much better in every way, it also has 3 stops of recovery minimum in shadows in stills and a6k you can barely pull a stop without ugly banding. Add in the shadow and HL tool, the touch control etc etc and the a6k is actually not that good overall, iq is certainly better from the Gx7 and I own both cameras, sorry.
ETC does have banding agreed, but hey what DSLR has anything like that, its limitations are there but its totally unique anyway? I think that Nikon and Canon need to provide evf based shooting at some stage for a proper hybrid experience for joe public, until then Panasonic are currently in a league of their own. The G6 is perfectly pitched to really give Nikon and Canon a bloody nose this time? if people just realise what the evf brings I would not understand why anyone would pick say a D3200/5200/D700 etc over the G6.