An awesome player took Nats, then Worlds with YoYoStringLab Plutonium (admittedly a string he helped develop and was sponsored for). He was of course happy with the string, but had a separate project in the works, so needed to remove the signature relationship. Regardless, he continues to use it and needed additional for a recent Worlds in which he took second by a minimal fraction. He could have used anything, but wanted Plutonium. In any case, there has been additional demand of course, but it’s still premium string, so it has been manageable to keep up with those that appreciate and feel the difference.
I think people are right that competitive players don’t always consider string beyond what they are used to. Fortunately, some do.
Regarding a YYSL nylon blend, I see it as a possibility. I know people are interested. It’s just putting in the time to do it right.