The first two images are the "before" and "after" shots from the Panasonic GH2 and the second two images are the "before" and "after" from the Olympus E-M5.
Panasonic GH2 before and after shadow slider adjustment
Olympus E-M5 before and after shadow slider adjustment
Clearly there is a difference between the before and after shots. But when it comes to comparing the two "before" shots to each other, and the two "after" shots to each other, I don't see any meaningful differences. I would have to conclude, at least for this scene, that the dynamic range of the two sensors is the same. That is, both captured details in the highlights and the shadows equally.
Off topic: I do feel that panasonic images have a bit more magenta in them, as seen in the black macadam driveway.
Larger files of the four images can be found here: