You said, "fluro" is more sensitive.
Sensitive is generally described as the ability to transfer vibrations from a source to a destination.
So, the implication is that a solid rod would be the most sensitive line available since the rod would transfer even tiny vibrations due to the composition of the rod.
From the previous postings, it has been revealed, that they typical fluro line in a given diameter actually stretches more than a mono line of the same diameter.
As a result, with less stretch - one has to conclude that Mono line is more sensitive than the comparable fluro line.
But, the entire discussion is about "semantics."
Rather than using a term like "sensitivity, or stretch, or invisibility in the water" forget about all of the words.
Rather use words like - "I catch more fish using fluro line."
No other words are necessary. Often, fishing is about confidence. If one particular line gives you more confidence about catching fish - then - by all means use that line - no matter what others say that are good or bad about the line.
This is all about "Free Choice."
Pick your rod. Pick your reel. Pick your line. Pick your terminal tackle.
Go fishing and catch a lot of fish to be either released or consumed.
Have a great day.