are you sure about that? i read it that all the sensors are identical its only the processing chip that's changed
That's when it gets tricky as it's hard to say. Some review sites might say it's the sensor that has had a slight improvement when they mean the processing chip has changed.
I've read in more than one review the mark 2 em5 has now got the same sensor as the em1 but you might be right and they mean the same processing chip.
The are all listed as live MOS so prob are all the same. The processing chip can and does then make the difference in image quality.