One thing to realize these days - the terms "nylon" and "flourocarbon" are pretty much useless in and of themselves.
There are now thousands of varieties of "nylon". Old Dupont Nylon had a sound - most people think of that when they say "nylon". It was a mellow sound overall. The Matin Crystal you mention, by contrast, has a lot more density than the original nylon and is as bright as almost all the flourocarbons.
Flouros are now entering the same territory when it comes to the variety of formulae. Some came be very soft sounding - others extrremely bright. Look at Worth Browns versus the Hard Clears, for example.
In short, don't judge a material by what it's made of - it's how it's formulated that's most important.