I thought the licenses are based on the per TB model? Of course your Symantec rep is the best source for this info.
Basically as far as I understood, there are only two options for this.
buy the appliance
buy xx/TB of capacity to unlock all features of NBU except deduplication
Buy xx/TB of capacity of deduplication you want to enable.
capacity is measured based on "Front-End TB's." Meaning, how much data do you want to protect or backup. Not how it's stored, replicated, or deduped.
The ala carte licensing of agents, tape drives, etc I guess would work, but the capacity licensing is what makes the appliance simple.