With the changes to smart healing and atonement, penance potentially won't function like it does now, the amount atonement is going to restore is being hinted to be lower than what it currently is and the random targeting being implemented for smart healing is going to mean it's not guaranteed to hit the lowest health raid/party member. If they do make PoH our high throughput AoE heal that's going to limit the amount we can cast it because of mana limitations so it's only going to be used for periods of high AoE damage. These changes leave disc without an efficient AoE heal that all other healing classes have, including holy's CoH and more potent renews. Holy Nova will also not be as strong as a monks SCK, Blizzard is categorizing that as a monk's high throughput AoE. I'd imagine it will be more akin to CoH or LoDs output, the only issue I see with the new Holy Nova is that every other classes efficient AoEs have some form of throttle on them, be it a CD, holy power, or being a HoT where the healing done is high but not instant. The current information about Holy Nova doesn't include any throttle, instant cast, no CD, it will just presumably be location based which is easily enough worked around.