mcjohn,
Most planes spend the night on the ground at the outstation. So, from a relative standpoint, the outstations have earlier morning departures than the hubs do, and the hubs have later evening departures than the outstations do. There will be a few single-city pair exceptions where there are heavy business travellers.
So, in plain English, you are more likely to find an early AM flight out of ATL on US than you are on DL. But as far as anything leaving that early, I'm thinking you are SOL. Nobody in their right mind travels that early. Wait, you can charter a plane, that will work!
Re: the comment about red eyes. I don't think red eyes qualify as repos anymore. When I travel on them, they are packed. And they serve a purpose for me, like if I want to skip a night in a hotel.