I have never heard of femoral shock before, but it sounds theoretically vaild. How likely is it to happen? It would take one hell of a shot on a moving, fully-intentioned opponent. But, so would a finger jab to the eye = small target, heavilly guarded, moving, and being used by someone who is not too happy.
Any leg kick works well if it effects the opponent's balance/center of gravity. If you get the shock value from such a strike - great! If not, at least you have chopped down the tree and put him in a less mobile/more accessible position. Once on the ground you can go Gangsta and apply liberal kicks to about anywhere.
A shot to the groin can work very well if the opponent is unaware, but like someone else mentioned - if they are ready for it, they might just grimmace. Any technique that relies on pain to subdue an opponent is risky in my book. Its better to make an attack the creates structural damage - usually a joint, neck, spine, bust ear drums, eye (if possible). There are a variety options.
Personally, I take many lessons from nature and almost all animals go for the throat. One of the best targets.... air, super heavy blood flow, tons of nerves, and the only skeletal protection is a highly-vulnerable chain called the "spinal collumn." Just about any hit to the neck will do tremendous damage (but take it easy on your Ukes/buddies).
My $0.02