I usually run Voidwalker if it's anything other than 34 & 35 arena, nightfall, or any hard raid. I akin it to, in my experience, being a line medic in the military. People will take greater risks when they're confident that someone can save them. They're a lot more relaxed, as well, thus making them better, when they know that they have someone that has their back if something goes wrong. It's more of a mental boost than a physical one. And it's noticeable when I play with my regulars.