For the sake of speed & directness, I would go for the spinning side kick as you describe. A true spinning side kick will bring you around a little more while lifting the knee similar to a spin hook and help with landing a kick that will score points by a judge for TKD sparring. A spinning back or straight back kick is also more direct and can take an opponent by surprise if they expect a spinning hook or cresant (What have you) but the back kick (Also known as the mule kick can hit hard like a mule or horse, straight back) is great for self defense, but it has a tendency to come up thru and under the gluteus and can turn into a groin strike or a strike below the belt very easily. Beware if you intend to use the spinning back kick for sparring you may under rotate your spinning side kick, then you may inadvertantly kick too low or get caught by a jamming or rushing opponent causing your back or side kick to hit low. The old MULE kick is great for defense, but for sparring it can cause some legal target issues accedentaly or inncedentaly. Change up is usually a good thing, ask a baseball pitcher, it keeps the batter guessing. Just try to be aware of what your change up can lead to. He saw my curve so I threw the HEAT and he knocked it out of the park. Once I was sparring at the U of M M.A. Club in the 80's, my opponent was a fencer. I caught him with a low round kick to the thigh, followed by a spin hook kick to the head. I worked great, but I tried it again. I did not think about the fact he was a fencer and was in a right lead, so as kicked low setting up the spinning hook and looked over my shoulder all I saw was a kenpo glove in my face. TAG! He got me. LOL. JMO. PEACE JIMI
