Everyone's eyes are a little different with these comparisons.
I believe that we shouldn't be looking at JPG shots unless we can back out just how much NR was used, either in-camera or if any was done in post. Based on the clear differences between the RAW shots and the JPG with this DPReview tool, it appears that the RAW files are not noise reduced and the JPGs are quite heavily noise reduced.
And as each camera body does NR slightly differently, we should be comparing RAW for the cleanest sensor comparison.
So with my eyes looking at RAW shots (center only), I saw the following shots showing similar levels of noise:
5D3 at 6400
7D2 at 3200
7D at 1600
That would imply -- admittedly, ever-so-crudely -- that the 7D2 offers one stop better noise performance than the 7D, yet still one stop worse than the 5D3. That's respectable from a 'look how close APS-C can get to FF these days!' perspective. But on the other hand, given the the five years since the 7D was released, current 7D owners might feel a bit let down on how little Canon have improved the noise performance of the sensor.
- A