I tested  the high ISO to compare with E-M5 using tripod, still most of the time  high ISO is needed when using  handheld.

So I choose the same subject  with an indoor harsh lighting of an incandescent bulb. 

ISO 200-800

This is where the strength of E-M1 mark ii is really obvious.  Combined with the much better image stabilization, I can easily get a one stop better performance. With E-M5 ISO1600 provides good compromise between camera shake and the high ISO noise. But with E-m1 I can get sharp image the with ISO 800.

 

ISO 1600-6400

The metering is little bit different between E-M1 ii and E-M5, E-M5 appears little brighter but lost details in the highlight. In the yellow lemons there are hardy any details where as E-M1 preserved the details.

 

 

ISO 8000 and up.

These doesn’t look usable at 100%,

If I compare them at typical viewing size..the colors are well retained with E-M1 ii.

 

 

Conclusion

I pretty much never used beyond ISO 6400 with E-M5, I do get very usable image till ISO 12800 with E-M1 ii, though it has noise , it’s almost like uniform grain with the colors preserved to most part.