Vaults should never
ever use att:friendly, as mentioned by nicolae. Besides causing unpreventable piety loss with Okawaru or Elyvilion, if the player manages to get the monster out they have a very powerful ally. Even if you think the monster would be too weak to be relevant, remember polymorph. There's a reason permanent allies are only given by Gods and the Mercenary card. Use att:neutral instead, like the halflings in the hungry kobold vault.
What's with all the plants lying around? The snozzcumbers should be enough for anyone the get the reference, and plants in D look a bit weird.
You should the NSUBST command to further randomize the positions of the monsters. Hard coding them like this is weird.
I think having a space of just two floors where the monsters are different is odd. Remember the runed door let's you have a bit more variance in difficulty- and the player can always teleport away.
Have you tried compiling the game so you can add the vault? Generally, not doing so is considered impolite, particular if it fails to compile and the dev who is committing them has to fix it. You can get instructions here:
http://gitorious.org/crawl/crawl/blobs/master/crawl-ref/INSTALL.txt. Then, you can use wiz-mode to test the vault.
Anyway I'm also surprised nobody has made this vault before. It's a cute reference and it's nice to see the snozzcumber's origins acknowledged in game.
On IRC my nick is reaverb. I play online under the name reaver, though.