Serpent's Fang - worth building around?

[Reynard_the_fox]

I've just started a Serpentine bloodline gnome in PFS, and realized that I have these cool fangs that are completely useless because of my low strength score. On the other hand, with a bit of work, they could be a really potent weapon.

Since I was thinking of making this guy into an infiltrator anyway (via invisibility, reduce person, etc.), would it be worthwhile to take Weapon Finesse and maybe one of the Beast Shape spells and going for the stealthed bite?

First, for reference, here's the Serpent's Fang ability - it really gets worthwhile at 7th level, where it requires 2 saves to heal.

Serpent's Fang:

Serpent’s Fang (Ex): At 1st level, you can grow fangs as a free action. These fangs are treated as a natural weapon inflicting 1d4 points of damage plus your Strength modifier (1d3 if you are Small) plus poison (Bite—injury; save Fort DC 10 + 1/2 your sorcerer level + your Constitution modifier; frequency 1/round for 6 rounds; effect 1 Con damage; cure 1 save). At 5th level, these fangs are considered magical for the purpose of overcoming DR and the poison damage increases to 1d2 Con. At 7th level, your poison requires 2 successful saves to cure. At 11th level, your poison damage increases to 1d4 Con. You can use your fangs for a number of rounds per day equal to 3 + your Charisma modifier.

And here are my stats:

Stats:

Str 6
Dex 14
Con 16
Int 12
Wis 10
Cha 18

Let's suppose it's 8th level and I've taken Beast Shape II, which allows me to turn into a Tiny or Large animal, and gives +4 Dex, -2 Str, and +1 Natural Armor (which I fear doesn't stack with the Serpentine Bloodline's NA). If I have 4 ranks in Stealth and a +2 Belt of Dex and I transform into, say, a Viper, I would have a Stealth check of +17 (including the bonus for being Tiny), an AC of 18 (bumped to 22 by Mage Armor and 26 by Shield), and a to-hit of +11 (or +13 and no dex bonus to the enemy if I'm invisible).

I'm imagining that eventually, I'll be able to use Greater Invisibility to bite an opponent a few times and run away, giving them an almost impossible to save against poison that whittles their Con away to 0 over the course of a few rounds. (Remember, every point of Con damage they take lowers their Fort save, leading to more Con damage, leading to a lower Fort save...)

Do you guys think this is viable for Pathfinder Society? If not, is Weapon Finesse itself worthwhile? Thanks for your critiques!

PS: Mage Armor and Shield continue to work when transformed, right?
PPS: If I choose to become a Raven, can I still cast spells with verbal components?
PPPS: The Polymorph subschool says that sorcerers maintain their ability to get claws, etc. while transformed, so I assume I keep my fangs and venom.