The (Vivaldi) clock is pretty much set and forget, I know. However it does need to be switched on/of together with the other components. I also switch the lcd panels off during playback sometimes (now I do that with a Pronto or Logitech remote). There is also dither.
On the whole I just like to see the status of the complete stack in Mosaic.
Just to feel complete. 
It would be cool to be able to control Rossini’s Master Clock settings via Mosaic. I understand I would prob need an RS-232 connection to the Rossini DAC.
There is no provision to control an external clock as there’s no communication pathway between the device that has the network processor and the clock itself. Vivaldi’s ability here is maxed out as all possible communication channels are devoted to the upsampler link to the DAC and Transport. Rossini does have the option of connecting the clock to the DAC via RS232, but that’s only to synchronize the standby function.