For a traveling Zeiss (and other manual/alt lens) shooter the 6D seems perfect, rugged enough but lighter and smaller than the 5D2/3.
It has interchangeable focusing screens, unlike the 5D3. Wifi/GPS I have no use for, but silent shooting mode is nice.
Also, getting robbed or smashing the camera to a rock somewhere will only hurt 60 % as much compared to the 5D3.
It will be interesting to see how the sensor performs, native iso 25600 sounds pretty good.