PE Seat comfort alone makes it worth it if you aren't absolutely penny pinching, and sometimes it isn't even much of a difference. AA's seat product is quite good, foot rest issues notwithstanding. The real key is that if you are booked into paid PE, they're going to have to honor that if they do cancel out your flight and you need to switch flights. If you're going economy and hoping for an upgrade to C, your chances shrink with each flight cancellation.