I am nowhere near an expert and my experience is only with trout, so this may not hold true for you.
Here in BC we are only allowed one line per fisher, so I haven't done side by side comparisons.
Two years ago I tried hi-vis line for the first time and tried two rods with the same setup except one used flouro leader and one didn't have a leader.
Again I could only have one rod in the water at a time, but it did seem that I caught more fish with the leader setup on a consistent basis.
If I try an experiment in the future, I will use a diary to keep better track