Frankly this time Riot is not going far enough. While i think Soraka is ok, and that the gameplay decision changes she brings to a team fight are a welcome change. I can see how Riot does not like her "burst" heals, and finds Soraka annoying. So if Riot wants to introduce a Heal over time mechanic, I agree with this change, but they should take this farther and give Soraka some damage back so she can be a dynamic character that can make a difference in a team fight and in the lane.
I would make the following changes: 1> THe PBE changes to Q are a fine idea, but i would make Rejuvenation a stackable buff that lasts 8 sec, that can be kept or transferred with using W, and reward people for hitting a champ with the center circle by making Q hit champs in the center aoe take 200% damage and gives Soraka 2 Rejuvenation stacks per champ hit.
2> I would change W to Astral Infusion CD 6sec 5% max hp, 40 mana
Restores 80/110/140/170/200 (+.9 AP ) health to another champion ally.
If cast while affected by Rejuvenation, Soraka will transfer 1 rejuvenation stack to the ally these stacks last for 8 sec and refresh the timer on existing stacks.
Cannot be cast if Soraka is below 5% health."