Which office instant messenger is the best for secure office communication?
1. CD Messenger (http://www.cdmessenger.com)
2. BigAnt (http://www.bigantsoft.com)
3. Cezeo (http://www.cezeo.com)
cryptocat, the only secure chat service. but then theres the security VS simplicity of use
Depending on your existing structure maybe Lync is an option?
I have never (actively) heard of the solutions you mentioned so for security I would suggest to setup your own XMPP server e.g. using Openfire, ejabber or something like that.