Up until this year I have never used a mechanical broadhead at all. I've been a fixed-blade guy my entire life. I figured it was time to try something new out, so after shooting a few heads I went with the NAP Spitfire Maxx. If you're familiar with the Spitfire it's basically the same head with a razor tip and larger 1 3/4" cutting diameter.
Yesterday I shot a nice buck and hit him about 4" forward. When the arrow hit I heard a loud "THWACK", he let out a grunt, and tore off. Afterward I could see about 1/2 of my arrow on the ground so I got down to retrieve it. There was blood a good 6" up the shaft from where it broke off, which was a great sign. After a quick 60-70 yard trail I found my buck piled up just out of sight from my stand.
When I gutted him out I found that the broadhead went through one lung solidly, put a big slice in the other, and nearly cut his heart into two pieces. Unbelievable the damage this head caused. I also stuck my finger into the entrance hole to confirm the head went through the shoulder blade (luckily in the flatest/thinnest area), and then busted a rib on the other side before the tip protruded from his hide. When I pulled the broken part of the arrow out of his chest the broadhead was in perfect condition. Aside from a few nicks in the razor tip it looked like brand new. No broken or bent blades or any damage to speak of.
Needless to say I'm pretty much sold on the toughness of these heads. I was really expecting to find a mangled broadhead and was pleasantly surprised to see it held together perfectly.
In any case, check them out if you're in the market for a new head. I highly recommend them.