I'm with Peter with the Nitlon, I now have it on all my bait casters, although I only use it up to 30lb even on the spinning reels as I go to its big YGK brothers Jigman and Ultra Castman for 50lb and over, mainly for the depth and length colours.
I tested some super fine 10lb Spiderwire Stealth tonight, I just formed a loop off the spool with an 8 turn uni knot and put the loop on a snap swivel fixed to the scales, I pulled the line buy grasping the spool until it broke at just over 8kg on the single strand about 50-60mm above the knot, did it a second time for the nearly the same result, 60-70mm above the knot was the only difference.
I was surprised the knot and loop on the snap stayed in one piece to nearly 18lb