I received a question earlier today about whether the Panasonic GH4 can continue to output from the HDMI while simultaneously be connected via WiFi using the Image App. The answer is yes, but you will lose the on board LCD screen. You should also connect via WiFi before connecting your external HDMI display. Here's a video showing how that works.
If you've mounted your camera to a balanced stabilizer, you'll know how handy this feature can be. As the camera moves around, a remote operator can click on areas of the screen that the camera should be focusing to. This works fairly well, but of course it will be dependent upon the lens used, lighting, and contrast of the scene. Facial tracking and tracking modes are also helpful when you don't have someone setting focus points remotely.
If you like that shallow DOF look, Just a reminder that for the Lumix 20mm F/1.7 lens, right now there's an instant savings of $80 dollars off.
Panasonic Lumix 20mm F/1.7 II Lens