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.
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.
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.
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.