Why do you want to ETTL, do you really just want to guarantee preserving the highlights at the cost of decreased DR and tonality ith increased noise? Can you not use ND grad filters and ETTR, maximizing IQ?
I just do whatever
works well for me in practice.
I meter for skin tone. Lighter materials with higher reflectivity however will blow out, even if the light hitting it is the same intensity as the light hitting skin tone.
If I meter on an eye that is in shadow, depending on the contrast the light side will likely be blown out. The highlights in the dress will certainly be blow out.
At a wedding I don't have time for 'redo's, it's not always possible either, most of the time if you miss a moment then that's it.. it's gone.. do better next time.
Not all camera's behave the same or have the same IQ. So to issue a blanket statement of always ETTR is foolish and will likely even be detrimental to the people who don't have noise/banding issues.
ETTR is fine in theory in a controlled environment where you have time to monitor your histogram and retake the shot if needed. It is particularly useful if banding/noise is an issue. The downside is you have to keep monitoring the histogram which distracts focus from what your trying to achieve, it means your much more likely to blow out highlights, particularly in run and gun situations in challenging light.
For me ETTL is much more practical in the 'real world'. The extra highlight recovery comes in very handy. I'm not saying I never want to blow out highlights, just that I would rather have the choice in post.
Pushing exposure 2/3's of a stop results in no perceptible banding issues. Noise on a FF D700 is very well controlled, so another non issue.
If I was shooting with a body that was more prone to Chroma noise/banding in the shadows, then ETTR would be a more compelling option in many more circumstances. However as I don't suffer from this type of image degradation (at least with the small amount I push exposure) ETTL offers more advantage than ETTR.
Now with the latest Exmor sensors, ETTR should be very seldom of benefit imo.