If I cast a World gorger Dragon, it removes the Sneak attack from the game, letting me keep the dragon in play permanently
I don't think that is technically true. However, WGD does do some interesting things with SA. The ability of sneak attack is both an ability, followed by a delayed trigger. Much in the same way you would still get the cards from Necropotence if it was removed between you paying life, and your ends step - your WGD still has that delayed trigger looming over his head.
Interestingly enough though, you can use WGD to "perm-out" -other- creatures you bring in durring the same turn. So lets say I pay

for a Serra's Avatar, then swing. After that is done I can then pay another

to bring in WGD who removes the Avatar (along with everything else). Now when the turn ends the delayed triggers start attempting to kill things. The Avatar is not in play so that one misses. Then the WGD gets sacced and the Avatar comes back into play and will no longer have the sacrifice trigger looking to kill her.
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For what it's worth, here is the deck I would play in multiplayer casual if I had a Zodiac Dragon. I tweeked it to reflect some of the cards in your manabase. I would probably play with fetchlands. At any rate here is the list:
Enter the Dragon.dec
4 City of Brass
4 Tiaga
4 Badlands
2 Volrath's stronghold
3 Sol, Petal, Diamond
4 Birds of paradice
2 Quirion Elves
2 Reflecting Pool (or gemstone mine, or something)
35
4 Sneak attack
4 Surviaval of the fittest
2 Vamp, Dt
2 Sterling Grove
2 Greater Good
1 Entomb
1 Wheel of Fortune
4 Animate Dead
2 Shallow Grave
2 Naturlize
1 Squee
1 Genesis
1 Scion of the Ur-Dragon
1 Nicol Bolas
1 Bograda Hellkite
1 Angel of Despair
2 Bladewing, the Rizen
1 Kokusho, the evening star
1 Kiaga, the Tidestar
1 Teneb, the Harvister
1 Zodiac Dragon
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There is alot of really fun stuff going on in this deck. When the deck is running like clockwork you have Survival -> dump A dragon -> find Bladewing the risen. Sneak in Bladewing, then animat the dragon. If it's Teneb then you have a good flow of dragon power. The other really powerful effect is to Sneak attack in that Scion of the Ur-Dragon and copy him into either Kiaga or Kokusho, then use the leaves play ability to do fun stuff. Lastly, you have Sneak attack + greater Good. Greater Good is for lack of a better word - insane - once you have sneak attack down.
Lastly Zodiac Dragon is also just kinda fun. You can Ur-Dragon -> Zodiac Dragon to get the Ur-Dragon back in your hand when it dies ... I think.
Lastly, If you can't get Sneak Attack online... but you have Survival, then you can Dump a dragon -> blade wing -> blade wing for -> anything. Then animate or Shallow grave the Bladwing to animate the first dragon for good. (then eat bladewing to greater good before he gets RFGed!)
So the deck can really work well with either Sneak attack or Survival. Also I really like Dragon Mage and Nicol Bolas. If you can get both of them online at the same time... thats just backbreaking.
Dragon Mage and Greater Good make me think the deck ought to be running some of the Spirit Guides. but .. maybe not.