From a healing perspective, Nightmare KP is tougher to heal than HM LI pre-nerf. Post-nerf HM LI is on par with Nightmare EV in terms of healing requirements.
I'm glad you agree with me
it is more difficult than Hard mode and Nightmare mode Ops
You need a healer in no less than full Rakata.
The rewards do not match the difficulty level.
Sentinel Marauder advice
Get a tank that moves the boss around the edge of the room. you cannot keep him still if you have melee in the mix. there isn't enough time to get the balls far enough away. stay behind him and help interrupt incinerate.