I don't like the 3 hours ahead of time either BUT that's b/c we've only used DME once and DME literally picked us up at CBR and took us straight to the airport. We left CBR at 5 AM and were at the airport by 5:45. I understand the 3 hour thing, esp during peak fight times but I wish there was a way they could be a bit more flexible if warranted, like in our case. IT SUCKED having to get up at 4:00 in the morning!
I was in WDW last month and had a 7 am flight, yes it was horrible getting up that early but I was also shocked at the security line that time of the morning. When I got in line I was glad the pickup was as early as it was.