I have quite a bit of high iso footage I can send you. PM me your email address and I will send some via wetransfer. From looking at your previous footage, you tend to shoot primarily wide angle, with video lights on the foreground/subject, correct? You won't get nearly as much noise with this kind of shooting. The background will be much more blue, as it is with the GH3 and GH3, but will be a much cleaner image then trying to shoot with all ambient, or requiring the camera to shift WB across the entire image.
Really thank you. You have a PM