Only got my GH2 a couple of weeks ago and test shots I've taken outdoors in the garden regularly hit around 22mbps. As I'd expect, lots of detail (leaves on the trees) tends to create files with higher bitrates.
Most I got so far is this shot, avg 22.4. Several layers moving in the wind, I bet this shot would go +35 on GH13. Worth noting that it breaks up too, especially looking at the bark of the tree you see that the codec suffers across the entire image in the video.
I maintain my position that GH13 is a better camera in the right hands. With big emphasis on that last bit. Of course, everything will change with a GH2 hack.