Experirience with using external XMPP/Jabber servers that authenticate using Zimbra

[MrSnivvel]

What is the recommendation for an external XMPP/Jabber server that uses Zimbra LDAP backend for authentication? I've tried using Openfire, but it seemed quite flakey on trying to setup, it didn't like LDAP backend for whatever reason. My Zimbra install is serving for 3 different domains, so I suspect it was related to that. I'd like to keep the XMPP server on the same box as the email server, just because there may be some clients hard coded to that value and since the server is already quartered off in the firewall. It needs to be able to run on a RHEL. I've glanced at ejabberd and jabberd2, but want to get others opinions before delving too deep.

TIA.