Comparison between Tigase, Openfire and any other open-source XMPP servers

Do not use Openfire if you expect to scale beyond a couple of thousand concurrent connections.

Tigase is amazing at handling hundreds of thousands concurrent connections and is wonderfully architected for largely distributed platforms where XMPP is simply the external interface. It comes with a price of rather poor documentation. You often need to go and read the source code to understand what's going on.

Openfire is perfect for small setups and its API is simple and very well documented. Unfortunately, it's not architected to scale even nearly close to what tigase is capable of.

Tigase is GPL(even version 3) licensed opposed to OpenFire being under Apache license ... for closed source application is OpenFire the go.

It is embaddable and proven to be reliable - 1000s of concurrent users. It even has gateways to communicate with legacy networks - like ICQ.

Only drawback I can se here is that it can handle only one domain per instance(port), however from your description that should not be a problem.

I totally agree with @Yuriy in that Tigase is great for high scalability whereas Openfire is more suitable for small, novice IT running chat for a SMB. I have gone into more detail on this in my blog on Tigase vs Openfire.