What are your settings for the EM5, shooting JPG.
As Viewer 2 emulates the JPEGs, it is theoretically a good way to try out the settings. Here's what I arrived at:
Picture Mode: Vivid
Noise filter: off
With these settings - in spite of sharpening and NR being at minimum - images are still sharp and noise free, and lack the artefacts of NR/sharpening. This is why I use the Vivid picture mode, as Vivid/-2 sharpening seems to produce a sharp image without artefacts (each picture mode has different sharpening defaults). I use -1 saturation to offset the oversaturation of Vivid picture mode.
I feel the contrast on the E-M5 is too high in all picture modes except Muted, so I set it to -1.
It also seems to me that the E-M5 usually underexposes by a third of a stop, so I'd set exposure compensation to +1/3rd as well.