I'm not so sure about the "minor priority" this would be a very helpful feature.
Any news on when this issue might get a fix?
I always used the grayscale image and focus peaking on the 5DmkII, so it would be great to have it on the Mark III.
I'm using magiclantern-Nightly.2017Jun17.5D3123.
This issue needs reverse engineering, and currently I have no idea where to look. That means, even if this would be the highest priority feature, I cannot predict whether it will take some hours or some years.
If you find this feature is more important than clean HDMI out or dual monitor support, just downgrade to 1.1.3.