If you're in legion and use light shot after dia on every mob, and mob dies fast enough that you don't have enough charges. You also spam both WF and last stand for different mob type, in such situation I don't think DP is very good choice even with higher base dmg. Unless you want to switch weapon and lose TP for every mob or SE fixed light shot dmg.
Keeping AM3 up on COR, especially in /ra mode is truly a pain in the ***. Probably even worse than other melee jobs. I agree that DP is a lot more useful in SoA though.