Blizzard has gotten it mostly right in their revised "downrank-lite" healing scheme. But what they didn't factor is Healers in Vanilla didn't downrank solely because of over-healing on the highest rank spells, we downranked mostly for the mana efficiency. It was always possible to uprank when absolutely necessary to put out a big yet expense and unspammable heal. And when I say "big" I mean a single crit could completely fill a Tank's HP bar.
The "greaters" of Cata aren't "boom" heals. My best crit has been for 1/4 of Tank's health bar. It should be double that. I know Blizzard wants us using the "goto" spells for our class. And for mana's sake every Healer will. But we need that slow, expensive, powerful heal in our arsenal. And right now it just isn't there.