6D - sensor measurements and comparison with other Canon FF

you're right 

Yes I think so. I see no other explanation (you can't really make a mistake in measuring dynamic range, it's just a ratio between two figures, one is noise and the other a fixed value). I have measured variations of 0.2 Ev between different bodies, therefore even a difference of 0.4 Ev between two extreme ones is not impossible. Imo, the second decimal in the DxO chart means nothing, and even the first decimal shall be taken with caution. Even if people sometimes expect the Holy Truth (with capitals) from those charts, they are not destined to be watched with a magnifier! 

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Thierry Legault - www.astrophoto.fr