Google Cache if you are experiencing an error 504 gateway timeout:
http://webcache.googleusercontent.com/search?q=cache%3Ahttps...
edit: Increased the worker count to 8. Hopefully that helps a little bit.
edit2: Turned on memcache.
[1]: http://serverfault.com/questions/30705/how-to-set-up-nginx-a...
Especially since you did it without any citation/reference (and since FDL notes that they did the legwork on this).
Edit: I'm going to give the OpenWatch guys the benefit of the doubt, and assume that they never saw the FireDogLake post, and that they were linked directly to the PDF of the letter that is hosted on DocumentCloud's S3 account.
It would be nice if they acknowledged the original source of the letter.