Your spec is good, but glyphs need work.
If you're going for Haste as a main stat (Which is basically what Shamans do these days. I saw one that had 50% unbuffed.) you're going to be using lots of Chain Heals. The Chain Heal glyph is a good one. Water Mastery I would recommend replacing, unless you're really having very bad mana problems. And the glyph of Healing Wave is garbage. I tried it out back when Wrath first started, when it was only Naxx, Maly, and Sarth, and the only fight I really saw it being useful on was Loatheb. Get the Earth Shield glyph to replace Healing Wave. If you end up being fine on mana, replace Water Shield with Lesser Healing Wave. Or, I suppose if you are purely raid healing, Water Shield is better.
I don't have experience with Purified Lunar Dust, but I do know that Solace of the Undefeated is a very good trinket. That's a keeper.
I've seen some Shaman's who have even less MP5 than you and even more Haste, so I do believe you're on the right track.