The fact that no devices are appearing in the Bluetooth pane is an indication you have no Bluetooth connections and can safely turn Bluetooth off.
Note that if you make use of AirDrop to send files between your Mac and another Mac or an iOS device, you'll need to have Bluetooth turned on even if you don't use any wireless input devices.
Good point!
If we knew what it was we were doing, it wouldn't be called research, would it?
