I believe with the Zumo, the power management is different pending which cradle it is in.On the Car cradle, with the Zumo off on an unswitched power connection, the car will continue to charge the Zumo battery.
On the motorcycle cradle, with the Zumo off on an unswitched power connection, there is no power to the Zumo.
This is correct but power continues to the unit from its internal battery. It gives you a choice as to continue on the Zumo's battery or let it shut down. If you choose neither option, the unit shuts down .
As for switched or not switched, I prefer the unswitched power to a GPS. If you have a switched power connection to your GPS, every time you power off the motorcycle, the GPS will have to go through it's boot process and re-establish position which takes a little time. If you have a direct powered connection, and stop for re-fueling or a quick stop, the GPS can stay on, and when you are ready to go -- so is the GPS -- no waiting for it to go through it's power-on sequence.
This is where the Zumo is different than other (I'm assuming) GPS units. If you touch the "yes" button (on the screen after turning the bike off) the Zumo stays active, being powered as stated above. When you restart the bike, Zumo switches back to the bike's power supply. No need to go through the reboot process. This also retains elapsed time and distance traveled (if using this function) of the current trip.
The only draw-back for having constant power to the GPS, is remembering to turn off the GPS.