I've seen a post months ago about how The Blackest Night (TBN) to Bloodspiller(BS) usage is a DPS gain only when in Grit stance. That was way back.

Now that there were 20 potency buffs for Souleater and Bloodspiller each, does that upset the rule?
Potency per GCD of Souleater combo = 150+250(+70 accounting for mana gain) + 300 = 770, divided into 3 (# of GCD) = 256.666...
Comparing that to potency of TBN-BS = 400 - 140 (accounting for TBN mana) = 260

PPGCD (256.66) < TBN-BS (260)

Does this mean more TBN-BS usage is a gain even out of Grit??
I hate to believe Devs would want DRKs to spam TBN for DPS gains, making the game play repetitive and stressful. Am I doing the math wrong?