I've done some testing in Shatt as blood. From what I've experienced Necrotic Plague is pretty mandatory right now. Blood runic power regen is pretty crappy. I don't think they are gunna nerf NP though but rather fix bloods RP regen in another way. Even on a single target fight with NP our RP regen seems a little low. I know that on live we are GCD capped and they wanted that to change but I think they took it a little too far.
Now one thing I've noticed that's pretty overpowered in an AOE situation is how NP, Conversion and Enhanced Death Coil work together. Conversion converts RP into 2% of your max hp every 1 second. When I was trying this on the pack of 5 dungeon tank dummies, I was able to keep conversion up constantly and I could still use death coil every few seconds. Since death coil increases our max hp by 5% for 30 seconds per stack with enhanced death coil, I was able to keep about a 8-14k per second stream of healing on me. That's quite a bit of self healing considering it was endless.
I haven't tried this on single target yet but I would assume I would run out of RP much faster. I'm also not sure what the minimum number of targets needed for this is but I'd assume 3 or 4 would still work, you just wouldn't be able to death coil as much. Either way it's pretty OP if you have a pack of adds that will live for a decent amount of time.
Next time I play my dk I'll pay more attention to the damage output from NP and get some comparisons with FF and BP. I might be able to get some logs going.