I redid this ISOLESS test, this time using my newly acquired Adobe PSCC (2015) plus ACR 9.2.
This is the logical progression of the experiment in "ISO-less" using a Nikon D7200. Images were taken at ISO 200 - ISO 12800 using f8.0 and 1/5 second exposure. ISO 1600 was 'properly exposed'

The files were opened @100% default settings except for a simple EV exposure compensation to normalize the images. In this case default means Adobe Standard profile and process 2012

These are all 100% crops out of 24MP files. Here we have ISO 200, ISO 1600, ISO 3200. ISO 6400, and ISO 12800. I included the same ISOs as the previous experiment
Clearly this 2012 process and ACR 9.2 RAW engine work much better at maintaining the image integrity even when using the default camera profile instead of a flat one.
This illustrates that "ISO-less" works, or at least it works even better than I expected, for higher ISOs.

By far the best way to see differences in these crops is to layer/stack them in an image editor like Photoshop and toggle each layer on and off to A&B them. Obviously this is not practical on the web.

Because I was able to use Adobe Standard the image is not 'washed out" compared to the 'Camera Flat' setting used in the earlier version ACR and process 2010.
To prepare this JPeg, I originally stacked these images in Photoshop starting with ISO 12800 and thus that EXIF data