If you want to see some real world examples, check out this thread. As NickB points out, the bulk of the thread is a bunch if whiners and 5D fanboyz but there are a few posts in the thread with examples. It's an old thread but then the 5D is a very old camera.
Post #158 is interesting because it shows the 50D vs the 5D noise test pushed 2 stops viewed 100%. Pretty much no difference to my eyes.