I always thought that the main reason why one would use a battery back-up in an HT is so that it allows all the equipment to be turned off properly in the event of a power failure. When I turn-off almost all my components, they do not really turn-off, but instead go into standy-by: My PS3, AVR, Plasma, etc. Once the component is on stand-by, it is safe to disconnect or power it off. Going from On to Power-off is not recommended. I don't have a Power back-up, but this is why I would consider one. Maybe I'm wrong.
