Scorch Build --Follow

What do you think about this build?
http://www.worldofwarcraft.com/info/classes/mage/talents.html?2300550000230140300000005520201030303105210000000000000000000000000

Purpose:
To build a high-damage output fire build.

Purpose (secondary):
- low threat
- mana conservation
- PVP victory from random encounters

Reasoning (purpose):
I raid once a week, and the rest of the time is spent farming or questing. I've been a fire mage since forever, and recently experimented with different builds (arcane, frost, elemental, etc). Although I love fireball, it's really a mana hog and I often ended up overkilling things.

Threat was an issue, too, even with Burning Soul. Threat was not as much an issue with the few Frost builds I toyed with, but I have already made the spellfire tailoring set, so it's not practical to switch to primarily frost at this point (until maybe after I replace the set).

Reasoning (build specific):
As a fire mage, if I'm going for high damage, lower threat, and mana conservation, then it makes sense to go with scorch instead of fireball as the secondary kill spell (cast after pyroblast). Thus, there was little reason (if I'm not going to use fireball) to take the Improved/Empowered fireball skills. That opened up a few talent points to distribute into arcane for added damage (specifically +crit).

I opted for arcane because Arcane Concentration is really good, and I find I use Improved Counterspell a lot in dungeons. Thus, continuing into this tree seemed the best idea.

I'm critting around 33% from fire spells (36% with scorch/fireblast).

So, taking into consideration equipment (+fire/arcane), survivability, mana conservation, and the role of a mage in dungeons (dps, crowd control) -- is this the best build for my purposes?