I actually did it several years back. At one point I was even playing around with it at 8.4KW and it was going ok till I killed my Adaptto MiniE. After I replaced it I decided to tone it down so I didn't kill the next one.
I also did the same on a Crystalyte HS4080. Worked a treat and both motor's/wheels went together with my Fighter when I sold it earlier this year.
Pushing hubs like this to the limit was fun, but as many others state, it's not using the right tool for the job once you go that far over the rated spec. I would certainly do it again for the right situation, but where the opportunity exists to use a better tool (i.e. beefier hub, or mid drive) then that should be the first option.
As a point of comparison, my LMX64 with it's mid drive has the same pull at 2.5KW that my Leaf did at 7.5KW and doesn't need any cooling mods.