The difference is in the ring pack. The KB’s use the 5/64-3/16 ring pack and the DSS use a 1/16-3/16 ring pack. The thinner ring pack is way more important than piston and pin weight.
Thnks, That'a also interesting, I didnt realise that but I would have noticed sooner or later when ordering rings. Well that's definitely made my mind up for the DSS pistons.