I use 40lb for a "general use" leader when targeting multi species but If I'm pulling big gear like 7"-10" cranks, in Pike infested water, 80 lb is the go to weight for me. A plug that big isn't effected as much with the thicker fluoro really.
My rigs are tied up one end with a ball bearing barrel swivel, and on the business end bearing swivel / cross locks.
I use the Berkley brand (weight rated) black swivel and can't imagine anything that would cause something rated for 200-300 lbs to EVER fail under normal use.
http://www.berkley-fishing.com/berkl...eviews#start=5
I have NEVER had a bite off or failure. Used the same leader for years and likely hundreds and hundreds if not thousands of pike on the same leader.
Use the right materials, and there are no issues.