"modern synthetics" is also a loosely used term. Chinese modern synthetic is probably crud compared to USA modern synthetic. So, yeah, having an extra layer of U.V. protection for the cheap stuff that we run would be a wise move. I'm running the cheap chinese modern syn on the 4runner
Honestly, there isn't as big of a difference between 'the cheap stuff' and the good stuff as most people think. By all means, buy the best stuff you can afford. The 'fuzz' comment still pertains to all Dyneema 12-strand ropes and how it works. The largest quality gap is generally the quality of the secondary operations like splicing the ends on.....short bury lengths, not properly tapered, poor lock stitching, etc. There are only so many factories in the world making ropes though. I have had very affordable import ropes that where perfectly serviceable after 10 years without much, if any, special care.
In some ways, imported line can often come with 'more' of a colorant dye package. The imported ropes will often have a shinier appearance new and deposit more of that coating onto the fairlead as it breaks in. Good quality rope, that colorant is often much more evenly applied and the rope will have a softer feel when new and less deposits during the break in process.