1. Specifying a different domain under "Cluster Topology" seems to break things (unable to connect to database).
2. Even if I could fix issue #1, SSL certificates seem to be generated based on the hostname -- CSRs as well. Meaning Jabber will not connect because the name it is connecting to does not match the certificates "CN" field.
Not really - it seems best to just use your public email domain for the IM/P server(s): im.companydomain.com
Technically on IM/P 10.0 you can specify a different domain for end users than the one assigned to the server... however just putting it in the public company domain seems to be the option least likely to create problems.
I am pretty sure putting it in a .local domain can cause some problems with Collaboration Edge as well..