I quit

[Reynhart]

Blood Price MP returns in ST fight is a joke now.

But your single target MP regen doesn't rely solely on Blood Price. And as a whole, it's much faster to refill your MP now, especially if you're under Grit.

Also, there is some debate on this, but some people are saying the math means that Bloodspiller is actually a DPS loss to use due it being on the GCD and delaying the use of Syphon Strike.

This is misinformation, there is no "delay" resulting in a DPS loss. What can be a DPS loss is spending too much MP on Blackest Night instead of Dark Arts, but that's without considering the times where TBN is used for mitigation, and that BloodSpiller ignore's the damage penalty.