Please allow me to throw a monkey wrench into this conversation.
I have 12 lb. InvizX on a Curado 70, and it performs fine. But one of the reasons it performs fine is that the rod is a M/MF crankin' rod. I re-read your original post, and you don't mention the rod that you're using.
Personally, I would NOT put FC line on a hard-tip rod. I know, I know .... some people do and they have good luck. But I wouldn't. YMMV.
Secondly: there are three methods for rating line strength. I call them American Underrated, American Accurate, and Japanese.
American Underrated is like Big Game, CXX, McCoy Mean Green and Trilene XT. If you look at the diameter, it's in line with line rated at least a full step stronger. The manufacturer rates the line for the absolute worst possible conditions you can imagine and tries to insure that the line will come through for the fisherman.
American Accurate is just that; an accurate rating for the capabilities of the line, but rated for American ideas of line use. Trilene XL, Maxima Ultragreen and Stren Original are some.
Japanese rating are different. As you can see, American advertising of line characteristics is all over the place. There is no regulatory board with oversight capabilities.
The Japanese domestic standards are (evidently) based on some sort of standardized tensile strength methodology. This results in a slightly more optimistic test rating than the American rating method. In other words (and I approximate here), 12 lb. test Japanese Domestic is equivalent to 10 lb. test American Accurate which is equivalent to 8 lb. test American Underrated.
To muddy the waters even more, the Japanese have reacted to the love of some American fishermen for underrated line and are marketing line with tests not in line with the Japanese standards.
One of the characteristics that American companies take into effect is shock strength. Shock strength applies both to the straight line and the knotted line, but the shock strength of the knotted line (knot strength) is much more obvious. That's one area where fluorocarbon falls behind nylon. A stiff-tipped rod would, naturally, make it a little worse.
NO MATTER WHAT THE ADVERTISING SAYS, FLUOROCARBON IS NOT LIKE NYLON.
When I finally chose 12 lb. InvizX, I mentally put it on a level with 8 lb. Trilene XT. I think I got that right. For use on a cranking rod, I like it a LOT better than Stren or Trilene.
But I have no illusions regarding its inherent strength. I know it's rated by the Japanese system. I can live with that. ?
So ...... maybe you'll want to go with 15 lb. test FC line.
Maybe you'll decide you don't like FC line because of its reaction off a snag.
It's for you to decide.
Hope this helps you. jj
