I watched a video today of a person using the Pilotfly 3-axis gimbal with the GH4. I think the footage is amazing. He is literally running at one point but the footage is so steady, it is hard to tell.
I knew the Pilotfly was great for GoPro-sized cameras but I didn't know it could "handle" the GH4 with a beefy lens (12-35mm). Hopefully the market will be flooded with 3-axis gimbals with the conclusion of NAB this week, but even if it isn't, I think we have a winner here:
https://youtu.be/l79OpYwTFek