nginx-1.0.x+mod_push vs node.js

[Davide D'Amico]

Hi, I'd like to know if anyone is using nginx-1.0.x with mod_push in production to keep persistent connections on a website.
I'm little scary about the huge number of active connections my servers can mantain (10000 or 20000).
I'm using a DELL R200 with FreeBSD 8.2-amd64 with SAS HD and 8GB Ram, using these sysctl:

kern.ipc.nmbclusters=262144
kern.ipc.somaxconn=65535
kern.maxfiles=524288
kern.maxfilesperproc=131072
kern.threads.max_threads_per_proc=16384

If yes, did you evaluate pros and cons on nginx vs node.js or comet?

Thanks in advance,
d.