The only thing with 4-blades is they tend to leave a cross type cut vs the oval hole that a 3-blade does on the inlet side. There doesn't seem to be much difference on the killing side. I do tend to get slightly better flight from 3-blades. The only damage on a Muzzy that I have ever had was a slightly bent blade because it hit the front shoulder blade. Most times a double lung pass through leaves the Muzzy ready to shoot again. That one will be use for practice and a new one is put in its place.