Arnold, very interesting! In my experiments, changing the stylus from a small side radius (including an microridge) to a larger one kept styrene records from being chewed up. Other parameters were kept the same, so I have fair confidence that the size of the side radius is a core factor.
And yet there are individuals like yourself who report being able to play styrene records with microridge stylii and get no damage. 'Tis a mystery.
The V15VxMR had low vertical tracking force requirements, so that could be one factor.
Also, if you look at the second table here
http://www.shure.com/proaudio/products/djphonocartridgesandneedles/ssLINK/us_pro_djlibrary_phonographyou can see that while the 3.0mil front radius computes to 75um (which is per Namiki's design), the side radius of 0.15 computes to 3.75 (larger than Namiki's original design specifications of 2.5um).
It could be that Shure uses a variant of the MR modified to have a larger side radius.
regards, jonathan carr