Hangouts is pretty garbage, I preferred being able to see whether people were online/away so I knew if I would get a response if I msged them or not.
If that is the only reason for using Talk instead of Hangouts, then I wouldn't bother. In Hangouts you can tell when the person is online whom you are chatting to, this is shown by a small profile pic in the chat glowing when they are online and greyed/hidden if they are not.
Sent from my Nexus 4