I think it is a terrible thing to say Priests (especially Disc??) have too many AoE spells. They aren't spamming 2-3 spells like most other classes, but 4-5-6 (Holy the higher nr's), wich feels good!
Holy Nova.. Well, they will have to completly remake this not to be annoying as hell. I remember Twins in ToC, I think you do to.
It is too early to say about these changes, because we don't know what Disc will get instead of PoH, Renew, BH etc. Holy Nova, well.. let's see.
It is already a big difference playing Disc & Holy, they have completly different niches already. It is good they want to make them even more different; Disc - more absorb spells, Holy - pure healer, as they already are.
I think they should focus more on making PoH not group dependant, but I have been thinking of just HOW, and had several discussions on forums over the years, but no good solution. I am frankly quite happy we did not get Paladins Holy Radiance, wich is the most boring and brainless spell in game atm:P If Holy got the choice to arrange groups on their UI as they wish in raids, I would be happy *keeps dreaming*