ST are fine for track, stiffer than most lowering springs. Plus they are linear, better feel and more predictable.
You don't need ridiculously stiff springs for the FRS/BRZ for track use. Most people who are lapping aren't experienced enough nor using sticky enough tires to run 8k+. Even from lowering springs to middle of the line coil overs showed very little improvement (minus, height adjustable, "stiffness" dampening) in lap times.
Arguing the semantics between the lower end brands is just that. It's opinion based on whomever bought them before you. Just find a spring rate that you'll be happy with for 90% of your driving and get it from a well known brand (not going to knock upcoming brands, just makes life less complex to use a tried and test option).
I bought ST's based on the company they are with (KW), they are valved very well, and use linear 4k/5k springs. In which in my research is more than fine for an entry level driver. Once I grow of of them and get more competitive Ill be upgrading to a higher level system along with tires, etc.
Just my opinion though
