I can't get how libevent would change anything on your problem. Could you elaborate please, knowing PHP wont use such a layer internally anyway ?

Also, I would strongly recommand you to use ext/socket.
ext/socket is a very thin wrapper over OS's socket capabilities, whereas stream_ suffer from a much more complex layer.
For example, for socket low level option, such as SO_REUSE , ext/socket is much more suitable. http://www.php.net/ref.sockets

The stream_socket_server() function is implemented incorrectly on the backend.  For example, I'm unable to create a connection with an acl.  

I can create this:

tcp://0.0.0.0:someport

but not:

tcp://192.168.11.0:someport 

This would normally allow any host on the 192.168.11.0 network to speak to the connection.  Instead you get an error that it can not validate the hostname.  There is really no reason to validate it, it's a network and not a host.

Also, the default backlog, as seen in some comments is only 5, and not configurable similar to the built in socket() functions.

Here is the reason for the backlog option.  In this example, the default backlog of my system is 128:

sysctl -a | grep somaxconn
net.core.somaxconn = 128

I setup a stream_socket_server on port 2057 and I have this:

ss -lnp | grep "2057"
tcp    LISTEN     0      32        *:2057                  *:*                   users:(("php",pid=11297,fd=7))

You see, I have no way to set it.  It's that simple.