CineD tested the S5II Rolling Shutter, Dynamic Range and Latitude. The conclusion:
From a pure lab test perspective, it seems that there is no gain without pain: the new LUMIX S5 II has nice new features including solid autofocus, but unfortunately in the lab, it falls a bit behind the previous generation, the S5 – when pushed to the absolute extreme, to keep things in perspective.
Not only is the rolling shutter worse (1ms more in full frame, 1.8ms more in APS-C), also the latitude result is not as good – it finishes with 7 stops of exposure latitude, mainly because of banding artifacts in the shadows and a more blotchy noise pattern which doesn’t look as pleasing to the eye.
That said, the dynamic range results are very similar to the previous generation LUMIX S5.