As the blackened element shows, I've managed to scorch the wort once. However, that was extenuating circumstances where I really wanted to push my limits. I tried to make a IIPA, but had to collect more wort than my little 7.5 gallon pot could handle, so I split it and put 5 gallons in the kettle, and 3 gallons on the stove top. In an effort to quickly reduce the volume, I boiled with both elements (normally I heat with both, but boil with one, which produces a nice lightly gurgling boil) which produced a extremely violent boil, and a finished beer that tasted distinctly burned.
It has not happened before that incident, or since. Even though I'm using fairly short 120V 2,000 watt elements, scorching the wort has never otherwise been an issue, even with the very light beers. I think the very low viscosity of the wort, and the ability to readily mix keeps the risk of scorching to a minimum. However, if one were to use something like this in conjunction with BIAB, I could see the potential for issues to arise.