Im using fluorocarbon every where i can. Meat rigs, fly leaders, diver leaders, copper leaders, cheaters, downrigger rods, etc. Is it a must? No but the my tournament fishing mentality tells me that if it results in even one or two more fish, every trip out then it is worth every penny. I question anyone who tells you that it is not something that you need. Define need? Do we need line counter reels? No. Do we need down speed? I guess not. But with them we catch more fish. Guys can catch fish using straight mono for sure but they will be out fished by the guys going that extra yard. We all know its stealth abilities. While it may not be invisible, it certainly offers the best solution. I leader with fluoro for "stealth" with spoon rods and also flatlines in skinny water and short cores but I would say the majority of it use is really for durability. Fish after fish, it puts up with beating that mono just wouldnt allow. Its not just fish we have to consider. Charter clients, zebra mussels, nets, tangles, along with an occasional fish help shorten the life of any line. The durability factor is the most apparent in fly leaders and meat rig leaders. Unlike most leaders, these see a lot of direct contact between the fish and the line itself (most of that with a mouthful of teeth). Fluorocarbon's stiffness provides great action to a fly and meat presentation but In my opinion that day when a king has engulfed the hook and is chewing directly on the leader you will be thankful you are fishing fluoro.