Not as rare or as risky as you might think or expect.
Check out Kenji Fujiwara at about 8:31 against Dennis Taylor all the way back in 1979.
It's not that risky when you know what are you doing, and those guys (the 2 videos) really knows what they are doing.
If you start the combat thinking about your chances of failure all the time, then it's not like you're thinking things the right way, in my humble opinion.
I was just figuring the risk/reward ratio of that kick, nothing more.
