I quit

[Reynhart]

Eh, there kind of is a delay. Each Bloodspiller is delaying your Syphon Strikes and Soul Eaters by one step, both of which are generating your resources, MP from Syphon Strike and Blood from Soul Eater. Delaying resource generation can potentially result in a DPS loss in the long run, but whether or not this really does result in a DPS loss has to be math-ed out more thoroughly.

Syphon Strike gives you half the amount you need for Dark Arts, so people add 70 potency has opportunity cost. So, a full powered SE combo deals 150+390+70+420 = 1030 potency over 3 GCD...so 343 pot/GCD with 4800 MP spent.

Basic Bloodspiller is 380 on its own...so it's better on average than you double Dark Artsed SE combo.

With Grit, SS gives you one Dark Arts, so 140 opportunity potency, increasing the total potency at 150+390+140+420 = 1100 so 336 pot/GCD...again, BloodSpiller tops at 380 even before considering the impact of Grit.

BloodSpiller is definitely a DPS gain.