I know you didn't ask for opions on Mech vs Fixed but I'll throw it in anyway
I used Mech's previously and then switched to Muzzy fixed blade. I definately perfer the Muzzy's. I had Mechs not open when they went through targets, had their blades bend and become unusable after goign through a deer, had their blades break when it stuck a tree limb. Overall I am much happier with fixed blades, plus I don't have to worry about if I have enough KE to open the blades or how much KE I'll have at different yardages to ensure the blades will open.
Just my .02, take it for what its worth.