I think a lot depends on where you are fishing and how deep the water is.
In the bay near Annapolis - water clarity is very low , especially below 10 feet deep. Once down about 25 to 30 feet - it is very dark , even on bright sunny days. Here , I doubt flouro makes any difference in fish seeing the leader or not.
Farther down the bay near Solomons - water is much clearer and in shallows , fish might see regular mono leaders.
Not sure if that even bothers them - hard to prove. I've caught nice Rock on gaudy plastic coated wire leader rigs designed for Blues.
Flouro does tend to lay out straighter then mono. When chumming was really big - some guys made leader stretchers that kept pre-tied rigs taut. This made the mono lay out nice compared to mono off a spool. Years ago we could buy " mason " leader in 48 inch lengths. It was very stiff but was tough to work with.
I know a few guys have experimented with tandem umbrella rigs. Exact same lures came off opposite arms - one with mono , one with flouro.
They did not see any better catching on flouro. Now this was off Breezy Point where water is fairly clear. I laughed because the umbrella rig itself is bright shiny steel wire with gaudy snap swivels. Can not imagine a fish shying off because it sees a leader on that rig.
What could be more mundane than dying of old age or of natural causes when there is death by misadventure to be pursued ? Skip