Sorry, I tried to edit the above, but 'The time limit for edits has passed', whatever that is. :laugh:
To sum up the thread on TSG, basically DASS or GSS is treated twice, which actually makes it harder that typical 303 stainless, but the grain structure is tighter, so it conducts vibration better. Consequently, the player to like the 'feel' of the putter, although the steel isn't softer.
GSS/DASS isn't much more expensive than 303/304, but since it feels better and is used less often, these putters usually cost more.