Your spec is fine except for 2 points that really MUST be changed. The 2 points in State of Mind should be placed in Divine Touch. If you are tank healing as Holy, you are in Chakra: Serenity, and you aren't leaving it. There really is no reason to spec 2/2 State of Mind, at least I can't think of an encounter that would warrant it.
The one point I would suggest moving, but is entirely up to you, is the point in Spirit of Redepemtion. If you are having mana problems, you could place it in Veiled Shadows. If you end up finding that you are raid healing (and you have excess mana to spend), you could put it in Rapid Renewal so you can blanket a few raid members with Renew. Or if you find that you need just a bit more survivability you could put it in Blessid Resilience.
Now, in terms of Holy being a tank healer: due to on going circumstances with the healing situation in my guild, myself and a Resto Druid have been forced to 2 heal many encounters. Its not terrible but I've found that Holy can shine as a "tank healer" on Heroic Chimaeron (http://www.worldoflogs.com/reports/t24n0wywjxfze6c4/sum/healingDone/?s=9143&e=9448
). I sat in Serenity and used the Holy Word to my advantage. Yes, its sloppy and so hard on mana to Flash Heal but it gets the job done.
However, on a different fight, Heroic Magmaw, I don't think there is any way I could successfully 2 heal it as Holy. I specced Disc to be the tank healer and damage preventer. It works well.
During the start of Cata raiding I found myself hanging out in Chakra: Serenity quite often, being the "backup" tank healer. In reality, this isn't necessary. All other classes are really more suitable for tank healing than a Holy Priest is, even in Serenity.
I guess one of the better examples of how I set up my healers would be Normal Nefarian. For our first few kills it was myself as Holy, a Resto Druid and a Resto Shaman. It looks like all raid healers, right? What the hell do you do without a H Pally/D Priest? Well, I placed the Resto Shaman on the Ony tank and the Resto Druid on the Nef tank. It worked well. In your case you could sit in Serenity and keep up the Ony tank, since he takes light damage. The H Pally may be better suited to heal the Nefarian tank, while your second H Priest focuses on keeping the raid up.
I really don't think you NEED 2 tank Healers on each fight. You can sufficiently get by with one strong tank healer (H Pally), and 2 raid healers. Make sure in this case you are always in Sanctuary.
Looking at your logs I hardly see any lightwell usage. That could be a big chunk of your healing right there. Train your raid to use it. Pick a spot to routinely place it for each boss and macro in something like "LIGHTWELL IS DOWN!" Mash the macro if you don't see Lightwell Renew popping up in Grid (assuming you track it via Grid of course).
Holy Word: Sanctuary is a mana drain. Most likely you are dropping it and the raid is easily getting topped off anyways. The only time I would really suggest dropping it is on Chimearon during Feud when everyone is stacked and keeps getting hit by aoe stuff. Otherwise don't touch it!
Glyph of Guardian Spirit and/or Lightwell (if your raid learns to use it), is waaaaay better than Glyph of Flash Heal. I actually use PoH, Lightwell and GS as my glyphs, switching out Lightwell for Renew when the fight lends itself to Lightwell disappearing (Ex. Conclave if you switch platforms).
Hopefully all of this helps @.@ Feel free to browse my WoL. I know its mostly heroic content but it will still give you a feel of what your top heals should be.
Good luck :)