A friend of mine uses one on the 5d, I think that for the gh is overkill. The adapter is huge and the 80mm f2.8 normal lens on the gh is to tele. the 50mm is f4 (the "cheap" ones). Nice lens construction and focus pull but I see no point to translate this to m43. If you get an adapter make shure it has tripod support.
@andres, could you post a photo of the rig? I've been wondering about that adapter. The Novoflex HARing and MFT adapter are over $300, which slowed me down some. I have the 60mm f/3.5 Distagon and the 110mm f/2 Planar.