DSS plates were different... a shallower bend angle made them very "friendly" with single tank diving (tank very close to your back). They also had a unique webbing retention. Lastly, the finish on them was superb. They really were nice plates. IMHO, only exceeded by Freedom Plates by Eric. They also had an impressive weight plate system to increase mass for dry suit diving. My long pattern plate with the weight plates is 16#!
Unique to DSS was the Long Pattern and X-Long Pattern plates for tall divers. Fantastic in how they fit...
I have long pattern Kydex and SS as well as an X-Long SS. Glad to have obtained them when I did. I feel they were a "game changer" for me with proper fit.