I use NAP Scorpion XP heads, and have killed a lot of critters with them. They are tough, and reliable. I have had sharpness issues with them, sometimes being dull as a butter knife right out of the box, but if they are, I just sharpen them. The Montec is an awesome head, but I have been unable to re-sharpen them, even with the official Montec diamond stone. Can't help but notice an absence of Muzzy users here, and considering my experiences with the way they fly, I'm not surprised.