Is there an easy way to toggle between test and live, or do you need to log out and log in to the other side?
There is a way to modify your Tessitura.ini file to use a different hostname. This is a workaround for the restriction that only one client be running on a machine.
On my primary workstation, I have 2 live and 2 test client instances ready to go at any time, so switching between any of them is as simple as alt-tab.