Other than in synced (leveling) dungeons where PS combo is stronger than just HS->SS without SE, and your initial pull, there should be no other use for it.

Except you have SAM/MNK (or any other high dmg dealing DPS) that don't use diversion frequently, and an OT that doesn't shirk you.
'Call me the power slash DRK!'

Yeah, the combo is a waste, just like any other enmity combo for tanks in lvl 60+ content.