I've used a jumping kick before in a real fight. I will never do it again unless I can catch them off guard when they aren't looking. In short a "sucker kick." That kick only works when the person doesn't have a chance to give with the kick, which is what naturally happens when we see something comes towards us.
My thoughts on this type of kick is. To only use it when you can kick someone similar to this.
"Flying kicks" just aren't for me. If anyone else has proof of one working when the opponent is facing the kicker, then I would like to see it. I would be interested how it was successful.