Another who wants late flights leaving. Last couple of trips we have managed to get on the 9:00ish flight out of MCO to ATL. Love it since it gives us the last day at the parks.
The one drawback I've found is leaving 3 hours early with a flight that late is just too early. I don't want or need 90 min+ at the airport. So a couple weeks ago we opted to do Uber to the airport instead. We didn't leave the resort till 2 hour before our flight and we still had close to an hour at the terminal. No lines for security that late. Earlier flights have found us in hellish lines.
Anyway, we just stay in the room packing up till 11:00, leave bags with bell services and spend several hours in the parks, before heading back to Resort, getting bags and calling Uber.