DRK is going to be Nerfed in Stormblood

[Hierro]

not enough? You didn't even played with those changes
lets test it first, than start crying

I can say these things because I have experience with the MP management of DRK. Think of it this way, the current rate of MP gain is as good as it's going to get. There's no debating that when blood price is gated by grit. So, if you're tanking gritless (and you currently should if you want to get the most out of DRK), you effectively lost a great MP source. To drive this point further, DRK will be using blackest night on cooldown to get the most out of bloodspiller, which itself is a big MP drain.

How is a free dark arts every 2 minutes going to offset that?