I do the PHX-DFW commute and its hit and miss. Some days it is super easy and they couldn't give a seat away and others, well, lets just say I have seen 10+ people on the oversell list and often see 20+ non-revs listed.

Now, I can usually get home on the flight I want but its not a sure thing. On the plus side, most of the flights are on the 319 so it has 2 jump seats which helps.