What you should be able to notice is that the GH3 loses detail more quickly than the OMD. The OMD, in my opinion, retains better sharpness. This may be due to in-camera settings, stronger AA filters, or how each camera is designed to process files. I made a comment a few months ago saying they were different sensors. This is proof.
I will not comment on dynamic range because I feel a machine can give you a more accurate opinion than a person.