Different RFC user names for different systems: I have a question related to the GuiXT Profile. We work on different systems, with the result being that we continually need to change the username and password. Can the "Special RFC connection parameters" option be used for this?

You can use different guixt.ini files for different SAP systems: use a SwitchTo command in guixt.ini and the variable &database (SAP system name) in the path for the new guixt.ini.