Has anyone ever used SMTP site links?

A simple real-life question, inspired by a comment here:

Active Directory has supported inter-site replication using SMTP instead of direct RPC since its first introduction in Windows 2000.

But did anyone ever actually use it?

If yes, why was it choosen?
Was it easy or troublesome to set up and mantain?
Was it reliable?

The reason you don't see it, and probably never will, is because it was designed to support networks which did not connect to or interact with the Internet. The Internet, and it's protocols (IPv4 and IPv6), have essentially "won"; it's incredibly rare to find a network that doesn't support them anymore. Even more so for a network using Active Directory.

I found this as a possible explanation in the technet article:

SMTP is best used between sites where RPC over IP is not possible. For example, SMTP can be used by companies that have a network backbone that is not based on TCP/IP, such as companies that use an X.400 backbone

Also, there exists the possibility that you can't have all the RPC ports open between sites (135 + high ports). Just using port 25 may be your only option.