We just used this for the first time, it's fantastic. Just like with a hammer, you can feel the spinner hit "rock bottom" and "hit back". No broken spinners or no dings in the aluminum wheels. The padded leather is nice too, no scratches on the spinners. I know you lead hammer and wood guys are sold on your method, but for the less bold, you should check this out.
http://knockoffspinnertool.com/
(See the one for the cobra, not the Jag or Lotus...)