I also had XP10 on my street Vette, wide sticky tires, etc...they were a bit much, dusty and sometimes squealed like a pig but I loved them anyway
I have had them on two or three other cars but they were seldom driven on the street.
For the ST I plan to do both street, autocross on occasion and quite a few track events, might end up with a BBK up front as plan to do suspension mods and run 225 DOT race tires most likely though I may just run something like the Yoko top street tire, still deciding on that.
XP8 may indeed be just right for most of these cars on track, I will probably run XP10 front and might go to XP8 rears as worked on my other FWD cars but then again I did have a bit of rear brake locking issues but addressed it with a Wilwood bias valve on the rear lines, worked great!