I got my GH4 today. Did a quick test at 4K. But I don't have the 280 mb/s card, only the 95 mb/s one. So I think it's a little jittery because of that and had to be recorded as an MP4, I again assume because of the slower card. I'll try to get the faster card this weekend. I have never used a Panasonic before, so I'm sure there are setting that I don't know yet. It's at 1600 ISO, I used the focus tracking setting and the 12-35 2.8 pani lens. But I think it's still pretty impressive. Here's a link to download the footage from wetransfer- http://we.tl/4Lvg0mW4Z3
Feel free to download and play with it for personal use. Just please, no inappropriate usage (adding sexually explicit material, etc...)
. And please don't post the footage anywhere else.
Hope this helps someone.
If anyone is in NY and wants to get together for a test let me know. I may be able to swing that this weekend.