For anyone else with this issue, i've managed to work around the issue by changing from the default shell to /bin/sh and then executing the command to dump the config.
Final variation file config for anyone else that needs it:
DEVICE_PRIVILEGEDPROMPT = "):"
DEVICE_INVALIDCOMMAND = "% Command not found."
COMMAND_ENTERENABLEMODE = "/bin/sh"
COMMAND_EXITENABLEMODE = ""
COMMAND_DISABLEPAGING = ""
COMMAND_ENABLEPAGING = ""
COMMAND_RUNNINGCONFIG = "cat /conf/config.xml"
COMMAND_STARTUPCONFIG = "cat /conf/config.xml"
COMMAND_DISCONNECT = "exit"
RESPONSE_STRIP_VT100ESC = "1"
RESPONSE_STRIP_ANSICHARS = "1"
RESPONSE_STRIP_NULLS = "1"
FULL_VTYPROMPT = "/home/cattools"
FULL_ENABLEPROMPT = "$"
It's also worth creating a dedicated login for CatTools to avoid having to exit from the PFSense menu system that is presented when logging in with 'admin'.
Cheers,
Martyn