Yes he has done it and it worked for a concert i guess but ime not that impressed with the final results,the work and understanding needed to go totally with ISO 100 and work the rest from the PP is not IMO worth it,j-see gets good results but no better than others on here with the tried and tested system.
It's hard to compare that Mike. I can compare my ISO vs my non-ISO but not vs yours since there are too many "unknown" factors in such a comparison. And we're showing JPEGs here while the actual advantage is in the RAW. About any cam will have enough quality left at high ISO to make it into a 8-bit shot.
Just give it some time and it'll be an as common (or uncommon) technique to shoot as ETTR.
It's not about my shot vs anyone else's but about my shot vs my shot. It's exactly identical as ETTR. Will I end up with a better RAW when I ETTR vs normally exposing? If the answer is yes, I don't do myself any favor by not using ETTR. The same is true for ISO. Will I end up with a better RAW when using ISO vs native ISO only? The answer to that defines the value of the technique.
For me on the D750 I have more benefits not using ISO. On the D810 this far I only tested up to 3-4 stops and the same is true there. Higher I don't know yet but I normally switch to the D750 for that sort of performance. The D750 does better there than the D810.
In the end it's about how much quality one is satisfied with. You can take good shots at every setting but better at certain. Some people are satisfied with good, some prefer better and then there are those that always want more than possible.
I suspect those satisfied with good enjoy photography most.