Like any class of technique, spinning techs have their place, if you develop the skill/experience of when to use them. They do carry their own unique risks, as well.
For myself, spinning back kicks tended to work best as almost a simultaneous counter…for example, if the opponent committed to a high back-leg right roundhouse kick, I might then spin counter-clockwise into a left spin back kick. Since he’s already committed, it’s difficult to avoid the counter. The spin back kick could be shortened up or extended out depending on the opponent’s proximity and still hit sharply if you land it.
With the spinning backfist, it could be either a follow-up to your attack, or as a counter. IME, it’s best when used in a combo and not by itself.
At the 5th International Kuoshu Championships in Taiwan in 1986, I remember seeing a Korean fighter matched against a European (Swiss?) Wing Chun stylist, who began the match in an obvious WC-type ready stance. They were still at a distance (possibly 8 or more feet apart?), when the Korean (left foot forward) very quickly launched forward, jumping off his lead foot and spun 360 degrees, closed the distance in the air and landed a perfect left spin back kick to the guy’s torso. It was the first and last move of the fight, as the other guy crumpled. He had never even made a move to defend against it, it was so unexpected.
I still remember that because, although it wouldn’t have been my choice to begin a match with, and although there was probably a huge difference in relative skill levels of the fighters mentioned above, it showed how fast, accurate and explosive some guys can be right out of the gate with such a kick.
