If you can kick high with decent power you can kick low with even greater power ... nothing wrong with practice in a full range of motion.
Tell Bill Wallace kicking to the head isn't effective. Ground to head at 75 MPH.
On the street I wouldnt kick someone in the head unless they were on the ground ... however in competition its pretty darn fun if you can pull it off.
check around 5 seconds in ... yup that's me sometime in the 90's.
http://www.youtube.com/watch?v=ZPWMyjGZECY
Just an extra tool in the tool box in my opinion.
BTW cool video Jamie ... like the Wong Fei Hung music.