I dabbled with AS for a few years and found the grass wasn't greener at all; F upgrades were much harder to get, the front line agents had less flexibility to help with issues I encountered, and they lost most of the international partners I was interested in flying to Europe (AF, KL, AM) leaving a really motley collection of lousy leftovers (BA, FI, EI, OY). AS catering is also worse than Delta's, and they have terrible terminal/gate assignments on the east coast (with BOS being a particular offender). And no PDBs (well, they supposedly introduced them, but the flight attendants rarely bother...)
The one case I'd say it makes sense to switch is if you're commuting on the west coast and would use the elite cancellation/change benefits, which are very generous at the MVPG/75k level on paid tickets. That alone might be enough to tip the scales...