I performed a quick test to display the various film modes in the GH2.
The tests uses a gray linear gradient image.
Unfortunately, I needed a larger image to shoot. This tests does not show anything below 18 IRE. I could not frame it correctly due to this
I'll perform this test later in the week which should show 0-100 IRE.

The good thing is it does show how these film mode curves roll into the highlights.
As you can see, Cinema has the most linear curve, but unfortunately does not appear to have much of a roll-off in the upper IREs approaching 100 IRE.
The good thing is Cinema has a decent linear response in the 55-70 IRE for skin tones.
Under controlled lighting, Cinema would probably win.
Unfortuantely, if you are working in "hard" lighting (direct sun), your shadows may get crushed due to the way the curve has little roll at low IREs.
Man I wish we had this linear curve, but with gently roll-off at the top and bottom. This would still maintain that fucking good looking skin tone, but would
also allow more light in the shadows and highlights would roll-off better before clipping.

Film mode Smooth does roll off the highlights better than Cinema, but it does punch up the upper mid tones. Compare the curve at 70 IRE (Cinema), Smooth is hotter which may tend to over expose your skin tones. I've seen this issue with Smooth. It looks great at the very top highlights 90-100, but looks too "peaky" in the upper mid and higher skin tones. I guess you could always throw a curve on this in post to bring down these peaky upper mid levels.