I just hit the line (Feb06 hire) living in Dallas. The previous comment is correct, there are quite a few flights to PHL from DFW. And usually one or two direct flights from DAL on Southwest.

On my limited experience, the flights are typically VERY full. I figured hub-to-hub would be easy to commute, but keep in mind you are losing an hour when you head to work.

The contract says you need to be at your airport in time to catch 2 flights that get you to PHL before your show time. To boil it down, the first flight you can catch leaves at 6am, and the next flight after that gets you to PHL around 11:45 as I recall. From that, you can only really commute to trips that start after noon. (assuming you can catch one of those flights)

Send me a message if you have any questions as you chew on it! Not here to steer you one way or the other, but just give a perspective. I know there are maybe 2 or 3 other DFW commuters in the company.