Thanks for the input.
I found
THIS POST where bmwdriver recommends NavCore 9.051 for the GO X30 (and provides a download link).
I only noticed a few differences:
9.205 will only send music to FM, instructions still play over the TT speaker, though it does mute the music while talking.
9.051 sends music
and instructions to FM.
9.205 uses time-of-day to control brightness.
9.051 uses the built in sensor as I prefer.
9.205 has full voice "Command and Control".
9.051 only has "Navigate to spoken address".
I also figured out through trial and error that the file that controls the day/night switching is ttsystem, not an individual file as I had hoped.
So I guess I will stay with 9.205 as I can live with the TT speaker being used for instructions and I much prefer the full voice command versus only having navigate to spoken address. I do like day/night switching via the light sensor, but switching by voice command beats giving up voice command and control for me. 9.051 with full voice command would be my perfect NavCore, but we all know you can't have your cake and eat it too:naughty:
Thanks again for the input.