Berlin Air Corridor comes to mind when thinking about keeping within the envelope. Sometimes over-speeding and stalling at the same time seemed preferable to an altercation with the hot and heavy things that seemed to be way within 5 miles of the wingtip.
Although I never witnessed it, one guy used to push 5k over the max height in a 1-11 if he couldn't go down, and ice was building up. So, he had the start of icing and a tricky airplane.
It was him that told the story, so not quite hearsay.