I would hope that full frame sensors you mention could out perform the crop sensor of the crop sensor of the 7D Mk II.
@KlausEnrique wrote:
@TTMartin wrote:
If this image had been captured with a Nikon D810 or a Pentax K-1. the image would not show such artifacts...
"Given the loss of detail in a 5-stop underexposure, ..."
More likely the result of overprocessing. Pulling something up from extreme exposure errors can have issues. However, I do agree that the newest crop of Nikon and Sony sensors are better than Canon's. I, too, think Canon needs to up its game in sensor technology. I am super impressed with the D810 and I want to try the new D850 as soon as I can.
You can keep the Pentax K1. 
Bob, you are right in that Tom's photo does not require superior dynamic range. It just needed for Tom to not make a mistake. But you know what, we all make mistakes at some point.
On your second point, however, unfortunately, you are incorrect. Low light performance refers to shooting, well, in low light. I am not sure if Tom was shooting in low light, but he probably wasn't. One does not normally shoot birds in flight in the middle of the night. How well does a camera perform in low light generally refers to: can the camera find focus in the dark? How noisy is the camera at high ISO?(which in this case, the 6D Mark II is pretty good). So, no, we are not talking about low light, we are talking about dynamic range, which affects not only photos shot in low light, but in all circumstances. Now, for all practical purposes, Tom was recovering information from the shadows (because he mistakenly underexposed his image). But even in normal conditions one may want to bring out the detail in the shadows, specially if you do not want to have your highlights all blown out! And some times you are hit with banding because of Canon's poor dynamic range.
The photo below was shot in the middle of the day. It is a 16 minute exposure. The highlights on the red channel are already blown out, but the blue and green channels have not even left the sensor's floor, so there is banding in the shadows. Even entry level cameras from Sony, Nikon and Pentax would not have that issue. This was shot with a 5DS which is not a cheap camera and has even better dynamic range than the original 6D and obviously way ahead of the 6D Mark II (although not as good as the 5D Mark IV). I already own the Pentax 645Z, which is even more expensive than the 5DS, but I still want to have a 35mm body with decent dynamic range (by 2017 standards). The 5D Mark IV doesn't cut it, but given that Canon already has advanced on dynamic range technology, even if it still remains the industry's laggard, to not include the meagre best that they can offer in this regard in ALL their models, is a huge disappointment.
@RobertTheFat wrote:
@KlausEnrique wrote:"Canon has steadily improved their dynamic range, it is malarkey that Canon hasn't improved their dynamic range.
The only reason I had a photo to push 5 stops to begin with was complete user error.
In every other case Canon has had more than adequate dynamic range going back to the original 6D.
If you need more dynamic range than Canon currently offers then yes, you should sell your Canon gear, and find another hobby."
I did not say that Canon has not improved their dynamic range. Indeed, the only reason I have stayed with Canon is that every now and then they do improve it. The bad thing is that it is still not good enough, as the banding in your photograph shows. Now, in your case it was user error but in other conditions it is not. Any high contrast situation requires good dynamic range: any time the sun is in your landscape, nightscapes, infrared (as mentioned on my previous comment), and even things like natural light portraits. Your assertion that "In every other case Canon has had more than adequate dynamic range" is simply not true. Just because YOUR needs might be fulfilled doesn't mean every other photographer's are. And maybe you should push your "hobby" a little harder!
So my point: given that Canon has improved in dynamic range as far as the 5D Mark IV (which is still well below Nikon, Sony and Pentax), it is perverse that Canon gave the 6D Mark II a worse dynamic range at low ISO than the original 6D...
Even if one accepts your assertion that Tom's picture shows banding, I think you're conflating dynamic range with low-light performance. Tom's picture doesn't require a particularly high dynamic range, but it challenges the camera's low-light performance by being five stops underexposed. Low-light performance is only part of a camera's dynamic range; the other part (avoidance of blown highlights) doesn't apply at all in this case. So why belabor it here?
