I was out looking at Christmas lights with my family and I took my 7D2 and one lens (28-135). Nothing else. So this is handheld at ISO 3200. It has plenty of shadows to show high ISO problems and some softness from being handheld, blown lights, and a wide open lens. Focus was, I think, on the lights around the front door of the house.
I'll go back alone and shoot at ISO 100 on a tripod in a day or two but I thought this would be a nice test of high ISO. As I think you can see, the noise cleans up nicely and the shadows look pretty clean to me.
Not a systematic test by any means, but a nice idea of what the 7D2 can do. I would not even have tried this with my 50D.
Looks a little like a table top set-up doesn't it. It's not.
A Merry Christmas to everyone