My main motivation was really for energy saving - I calculated that my server is only ever being used for about 50% of the time, so it seemed rather wasteful to have it running for the other 50% unnecessarily.
It is a clever idea to have the server hibernate for specified times - unfortunately, my son likes to record kiddie programs that are often on during the day, so it would be difficult to pin-point a windows when there is unlikely to be anything on.
The consensus, from various forums I have since read, seems to be that if it is a server, just leave it on all the time and take the hit on the electricity. This being the case, I am currently considering whether it would be worth upgrading to a new generation integrated passive motherboard, which shall use much less power - something like a J4205.