I'm sort of ambivalent about the SDC policy... $25 really isn't a bad deal to get to where you're going earlier, especially since you can confirm it without even being at the airport. The only time it's burned me was when I changed from Flight A to Flight B and back to Flight A - the agent still insisted on charging me for the change back to my original flight! I used my best persuasive powers to argue with her, but really wasn't up for it that day (relative was very ill), so I ponied up and bit the bullet.

One question... If I were to be flying, say, EWR-IAH-DFW, would it be possible to SDC over to a nonstop EWR-DFW? Or does the routing have to remain the same?