According to the DXO mark scores, no material improvement at base ISO compared to the older exmor sensor (D810 used as a proxy to the original a7r), but significant improvement at higher ISO. With the older exmor sensor (D810 and a7r), the DR advantages compared to the Canon are basically null by ISO 600 or so, but thanks to the signal boost (inherited from the a7s) at ISO640, the a7rII consistently has at least a 1 stop advantage over the 5DSR throughout the ISO range.
Note, the D810's composite score for DR is skewed, since its measured at a native ISO of 64. At ISO 100, the D810's DR is not materially better than the a7rII.
Color sensitivity is also consistently better than the 5DSR throughout the ISO range:
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Speaking of the A7s, the a7rII basically matches the low light dynamic range of the a7s up to about ISO 6400. From there the a7s pulls away, but is within one stop up to the a7rII's max native ISO:
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Color sensitivity is basically on par with the a7s. This is what has impressed me most about the a7rII's low light performance. The color fidelity is well enough in tact to make useable images at extremely high ISO:
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My interpretation: the a7rII's sensor is probably the most well rounded sensor in the market right now. It's a jack of all trades, master of none, but it has a resolution that is on par with the 5DSr, base ISO DR that is on par with the a7r/D810, and low light DR and color sensitivity that is on par with the a7s. Given that recent cameras have become increasingly more specialized, there is a lot of value in a sensor that can perform at a high level in multiple areas simultaneously.





I just got my own 24-70L II yesterday as well. Only thing I don't have is an a7R II. 


