Alright,
Well, I've Owned Both And Love Both. I Don't Have A Manix 2 At The Moment And Want Another One Badly. But Here's My Two Pennies. It Depends On What You're Looking For. The Manix 2 Is The Same Overall Length At Like 8" Overall.
So Length Isn't An Issue. The Manix 2 May Be Slightly Thinner. It's A Big Beefy Knife With The Same Blade Steel. If You Get The Benchmade 550HG You'll Also Get A Hollow Ground Blade, Like On The Manix 2, And A Thumb Hole. The Main Difference Is The Handles. The Handles On The Manix 2 Are Grippy Nice G-10. They Feel Nice And Solid. It's A Big Hard Working Knife. But It Also Weighs More Than The Griptilian. Light Weight Is Nice.
My Nice Cutter Is My Paramilitary 2. My Heavy Duty Blade Is Going To Be My Griptilian. It May Have Plastic-Ish Handles But They Are Strong, Thick, Light, Grippy, And I Don't Feel They Feel Cheap At All. It's As Solid Of A Knife As A Manix 2 But Less Weight And Heavy Duty.
Really You're Good With Either Choice. The Manix 2 Is Quite Wider Though.
They Are Both Wonderful Knives And You Can't Go Wrong With Either Of Them.