We run a number of Openfire XMPP/Jabber servers. Due to the way Openfire works, we cannot easily run multiple Openfire instances on one server, so I have 5 identical VMware ESXi VMs, each with CentOS, MySQl, Java, and Openfire. They're the exact same, except for their IP addresses, the actual Openfire MySQL database and it's config file.
I am wondering if this is the optimal configuration, or if it would be better to move these VMs to a single FreeBSD machine and put each one inside a FreeBSD jail. Specifically, I am wondering if the benefit of VMWare's Transparent Page Sharing (TPS) would outweight the cost of running 5 identical OSes. Would I end up using less memory with one large FreeBSD machine and java running in bsd jails?