Those 2 aurora shots are terrible. Noisy, coma in stars, chromatic aberration uncorrected. There are any number of people on this site who could've done a far better job than that. Perhaps we should offer our services to the Canon marketing Dept.
And I think they were trying to showcase the low light performance of the mark iii. Fail. I'm sure its better than that.
Low light ISO is more for indoors type night shots without a flash or perhaps early evening like weddings or dinners/parties. Otherwise a flash. So I am not sure what all the fuss is about high ISO performance in the camera forums as if its the be all end all. For astronomy I think its pretty meaningless as these shots show.
Unless you have a lens that does not give coma in the corners and chromatic aberration at the edges then you need to stop down. You need to track the camera and do longer exposures at modest ISO to avoid star trails and get some sharpness and signal.
This came home to me imaging comet Lovejoy over Christmas. The only shots I got that I was happy with were tracked.
I think for your work Humi this camera would be awesome, everything upgraded on a camera you were already really happy with.
Greg.