From your experience do the mechanical practice heads fly the same as the hunting head? Basically, should I shoot my Killzones and risk tearing them up or is the practice sufficient?
My Muzzy's don't. I always throw the practice blades away. I have three regular BHs that I just shoot for practice.
With fixed heads I just keep some blades for practice. I used NAP Gobbler Getters this turkey season and the practice blades on those flew exactly the same.