The STOS were a very good head. I still have some I am using on a very low poundage bow set up.
Always flew great and had an exceptional grind, one of the few "traditional" style heads that were pretty much at the touch up stage out of the pack.
The 130's had a reputation for curling on a hard hit. Application of a tanto helped tremendously but when we carried them the 160 was by far the favorite.
Closest thing to a STOS now is the Zwickey No Mercy. They cost less but don't have as good of grind out of the pack, and of course are only available at 130 grains, but unlike STOS single bevel and a four blade option are available.