1. Firstly the recording of the scene with the sole purpose of protecting the brightest highlight is a departure from the original concept of ETTR, although Riechmann has expressed that poorly in his article on the subject where it was first discussed. The intention of ETTR is to shift everything to the right, even though the original article is written with the quote "...bias your exposures so that the histogram is snugged up to the right, but not to the point that the highlights are blown." The intent however comes through clearly in the rest of the article where he says for example "...when you look at the RAW file in your favourite RAW processing software... ...the image will likely appear to be too light." and "...This will accomplish a number of things. The first is that it will maximize the signal to noise ratio. The second is that it will minimize the posterization and noise that potentially occurs in the darker regions of the image." So the whole purpose is to shift things to the right, not simply to blindly shift things to the left just to protect all highlights, including specular highlights, which should rightly be blown out.
2. ETTR is not a technique to use at any ISO other than the base or lowest ISO. If you are working at higher ISO, ETTR effectively lowers the ISO anyway and the best way to improve the image would be to shift the ISO rather than use ETTR. So exposing for the subject at higher ISO should be self-evident and ETTR should be ignored. It would be ridiculous to use ETTR and high ISO. That defies common sense. That is also touched on by Reichmann with this statement "...Also be aware though that by doing this you are in fact effectively lowering the ISO used to capture the image, requiring slower shutter speeds and/or larger apertures. If you are hand-holding the camera, or shooting moving objects, the tradeoff may not be worth the reduced noise level.".
So it would be good to see the scene that was shot to come up with these figures and to analyse it, because you shouldn't be shifting the subject left with ETTR, it should be going the opposite way.
Just two quick comments:
1. Firstly the recording of the scene with the sole purpose of protecting the brightest highlight is a departure from the original concept of ETTR, although Riechmann has expressed that poorly in his article on the subject where it was first discussed. The intention of ETTR is to shift everything to the right, even though the original article is written with the quote "...bias your exposures so that the histogram is snugged up to the right, but not to the point that the highlights are blown." The intent however comes through clearly in the rest of the article where he says for example "...when you look at the RAW file in your favourite RAW processing software... ...the image will likely appear to be too light." and "...This will accomplish a number of things. The first is that it will maximize the signal to noise ratio. The second is that it will minimize the posterization and noise that potentially occurs in the darker regions of the image." So the whole purpose is to shift things to the right, not simply to blindly shift things to the left just to protect all highlights, including specular highlights, which should rightly be blown out.
2. ETTR is not a technique to use at any ISO other than the base or lowest ISO. If you are working at higher ISO, ETTR effectively lowers the ISO anyway and the best way to improve the image would be to shift the ISO rather than use ETTR. So exposing for the subject at higher ISO should be self-evident and ETTR should be ignored. It would be ridiculous to use ETTR and high ISO. That defies common sense. That is also touched on by Reichmann with this statement "...Also be aware though that by doing this you are in fact effectively lowering the ISO used to capture the image, requiring slower shutter speeds and/or larger apertures. If you are hand-holding the camera, or shooting moving objects, the tradeoff may not be worth the reduced noise level.".
So it would be good to see the scene that was shot to come up with these figures and to analyse it, because you shouldn't be shifting the subject left with ETTR, it should be going the opposite way.