Is the EM5’s Miss-Stated ISO concerning to you?

Normally ISO applies to JPEGs only. Please read DPR's explanation:

The only other definition of ISO you're ever likely to encounter is one that can be used for RAW data. The problem is that it's based on a combination of the sensor's saturation point and a generic tone curve – which isn't necessarily the tone curve your camera's JPEGs or metering are based on.

btw, you might want to quickly retract your statement "So is the E-M5 really about 1 stop behind the GH3?".   It does not make make you look so good.