What is the flex progression for the highbacks? Like this?
Stiff ................................ Soft
SF45 > TT30 > DMCC Light > DS30
How would a stiffer highback soft baseplate differ from the softer highback, stiffer baseplate (I have an idea, but I'm interested in the design reasoning).
The flex progression I posted (via Lady Flintstone) was for the binding as a whole.
Based on the design of the highback, your highback flex progression should be changed to SF45 > TT30 > DMCC Light & DS30. Because the DMCC Light and DS30 have the same highback. Unless you opt for the DS30 Limited highback.
BTW, I'm not a rep and haven't tried either binding side by side, but I think Nivek has compared them.
As for your last question, I have no idea. But my guess is the DS30 Limited would be stiffer than the standard issue DS30.