That's what I figured you were getting at, since I hadn't noted any other mention of German steel in any other club's promo material.
Here's what I was able to find out about the so-called GSS inlay for the Scotty Cameron Studio Style Newports:
According to
this
site (Google cache page of SC's website), the steel that is called GSS is 303SS, which corresponds to Type 303 (Type A1 for ISO3506 numbering) stainless. The SS either stands for stainless steel, or less likely, denotes that there is added sulfur in the mixture. Type 303 stainless is a derivative of Type 304 (Type A2 ISO3506) stainless (your common 18/8 stainless, or what everyone knows as stainless steel) only with the addition of sulfur and phosphorus. All 300-series stainless is austenitic chromium-nickel alloy base. The added sulfur changes the steel in these ways:
- reduced ductility
- reduced impact toughness
- decreases corrosion resistance
- decreases weldability
- decreases tensile strength
- decreases yield strength
- adversely affects hot working
- increases segregation tendency
- increases machinability
The added phosphorus has these effects:
- reduced swelling rate
- reduced creep rate
- increased rupture life
- can cause pearlite banding due to segregation during casting
- increased intergranular embrittlement (if segregation occurs)
- increase in ferrite grain coarseness
Mainly all this adds up to is that the steel will be softer (due to the sulfur's lowering of impact toughness) and much more brittle (which leads to increased "feedback" and "feel" via vibrations through the club face).
In short, it's nothing special and is mainly one more thing they can use to sway the minds of less informed consumers. It is not unique, for the most part. It is possible get the same effect from a polymer insert. Really all the "GSS" is good for is fancy acronyming. Whether any other manufacturer currently makes an insert putter with the same qualities as the "GSS", I cannot say.