As far as I can remember GPS and ATTI works ok.
I only spent a few minutes trying out the Phantom TX-RX on the Naza M Lite. I switched back right away to the FrSky RX once I saw that I cannot assign a function to the 3rd position of the GPS-ATTI-ATTI switch.
I am also quite sure turning off the Phantom TX will not send the Naza M Lite into failsafe mode.