I'm not sure that I agree with the critique of he instep being a left-over bad technique from point sparring. Though, I think it would be misapplied to use it on the ribs or abdomen, on a whole due to the danger of elbows. Protection Aspect The instep kick is well adapted for any leg attack, especially to the outside leg attack. The toe kick would be great, save that it would be easier to break your toes coming upwards at such an angle to such a low and slanted target. The toes back are better suited to rib and head strikes with a full roundhouse (though due to the knee torque, the instep is still better suited for the 45 to the ribs, but with danger of the elbow block- though this can be considered offset by the additional speed granted by the shorter range and quicker motions of the 45 roundhouse) The shin kick is well suited for any attack, with the following downsides: The shorter length of the striking point from the fulcrum (knee or hip depending on the kick style) means that the striking point is moving slightly slower than the foot. The foot sticking out from the shin offers additional jeopardy to the foot being injured accidentally, or being snagged. The shin, while less susceptible to breaking, is more vital a break than the foot. When the shin is offered, a good strike to the shin may, in fact, cripple you for the fight and some time after (if you survive). Whereas with a defensively balanced foot kick, if the foot is injured, you may be hurt, but the immediate danger and long term damage can be less severe on the whole. Power Aspect: There is more hard force to the shin. There is more speed to the foot. There is more accuracy required with the foot, and less a striking area, meaning the same force is dispersed within a smaller area; it is the opposite for the shin. Training Aspect: With either technique, your foot is exposed to real danger. If you practice foot kicking, it is strengthened. If you practice shin, it is not. Training both would be a great idea. Tactical Aspects: If you are going to sacrifice the distance from shin to foot, you are already close to the range of a jumping knee kick. Ups and downs. I'll stick with my foot, but won't neglect the shin. Peace.