There are lots of different reasons for using a dedicated channel for administration, mainly, you use it if you want to:
1. Ensure secure administration (SSL required for domain admin channel configuration)
2. Separate admin traffic from application traffic. If an application is dead locking the managed server, you can still stop the managed server through the admin channel. (Of course, you can just use command line kill.)
I personally do not use it as it REQUIRES SSL to be configured on the entire domain, and the only benefit you get out of this is that your administration commands are hidden and secure (big whoop).
You should be blocking the administration server IP:port from internet via firewall, so that people cannot freely access your admin_serv/console URL. I really do not see any benefit of using administration channel besides guarding against disgruntled employee from sniffing your passwords/commands from the local subnet.
