I've never heard of a rotor in autorotation overspeeding to the point of immediate damage to itself or the dynamic components.
It's almost impossible to get a rotor system without power to get to such high rotor RPMs. Under power, possibly, but not in autorotation.
The problem arises Shawn when people either deliberately set the auto RRPM high or don't bother to check it when it slowly creeps up, as they often do when things wear.
They then have an extraordinary high auto RPM setting that if not monitored will give horrendous spin up and of course far higher ROD. Not a pleasant sensation to be watching 'some' flying schools doing autos and hearing the rotors spin up to that blue note. Stretches the spindle bearings like nothing else.
For the newbies, in auto there is only one power source and that ain't changed in millions of years.
Faster you spin them rotors gadgets, more energy you use, faster you go down. Always set them up IAW the Maintenance Manual and check it every 100 hours.
That will also give you much better throttle correlation instead of having to fight it.
Reminds me of a blog I often read and sometimes contribute to, it's Tim Blair's and he's a very funny man who excercises extreme brevity. Just recently he coined a phrase "Hit the Rotors". One bloke reckoned his grandad "Hit The Rotors" at 99. Struck a chord with me anyway. He was referring to the stupid birds that fly into these even more stupid so called green energy gadgets - wind turbines. A few days before that he had a hilarious thread on correct punctuation.
So do it right an' you won't "Hit The Rotors" too early.