Still getting to know our A7s but i can tell you that the Quality is staggering compared to the Canon 6D's that we have been shooting with up until now. the fact that you can shoot beautiful crisp wide shots and then Slow mo at 1080 50 is ideal. the 100fps is really nice too. Granted i have a lot to learn with the PicProfiles but for a start its a whole new world. Praise the camera gods for peaking. It is a lifesaver in this type of shooting. But don't rely on it for Interviews or portrait shots as you wont always get the Eye Sharp. Rely on your punch in zoom for that.
Trying to decide between the Sony and the GH4? Its all about what you shoot. They are both amazing for the cost. Choose the camera for what you film and not for what it lists on Paper.
Full Tough Mudder edit using this camera to follow shortly.