Anyone tried this one? Ashaway used to make a MonoGut - same name as this new string - but it was not a zyex string. Their Dynamite line, which has been out forever, uses many smaller strands of zyex surrounded by a nylon braid for durability. They apparently figured out how to make a string with just one big strand of pure zyex.
Zyex as a material is softer (less stiff) and more elastic (thus more powerful) than nylon. It's about midway between natural gut and nylon in terms of both those characteristics.