I'm plat and currently flying to DFW but through Vegas. However I'm flying out sunday and hitting the last flight (getting in at 1am) and seems like I barely made the upgrade. I did this route last year and was upgraded a very high percentage going through vegas. I wanted the extra segments and it was cheaper to do so. I noticed the flights directly to DFW from PHX were always pretty empty in regards to F by the 3 day window. Here is hoping you get it though.
Lance