I believe that the reason my Edge turns off and yours will not is because you've got automatic source switching turned on. My Edge turns off when I turn off my projector as long as my input source is not my Tivo.
It actually makes a bit of sense that the Edge remains turned on when there is an active source. It allows you to listen to music with your TV/projector turned off.
All you need to do if you wish to save electricity is to turn off automatic input switching. The price you pay is that you'll need to manually switch sources. Your choice is to save a bit of money or go through the minor effort of telling the Edge to change sources.
If I change to an unused EDGE input before turning off my display, I get a blinking red LED when I turn off my display.
Would you tell me how you are disabling Auto Input Switching? Also, just for clarification purposes, when you state that the EDGE goes into Standby mode, what color is the LED on the EDGE?