The word was that the M5 would have identical image quality to the Canon EOS 80D. Looking at the EOS M5 vs. 80D comparison, I see some slight differences. When I first loaded and compared the M5 results, I thought that I miss-focused the lens. Five tests later, I concluded that the M5 was turning in very slightly softer results than the 80D. However, it is likely the RAW processing is what is different. In DPP's Quick Check window, the M5 results are slightly sharper than the 80D results. In DPP's Edit window and in the processed TIFF files, it is the 80D that appears sharper.
What I think I like better is the EOS M5's reduced high ISO noise grain.