Ok, here's an update (from the AUS-LAX flight earlier spoke of).

I woke up this morning and sure enough, no upgrade. Got to the airport for kiosk check-in, and it said I was already on the airport standby list. Got to the admiral's club, and the wonderful ladies there said I was on the Comp. list and not the SWU list. Once it went to airport control, the kiosk automatically put me there. However, one seat for sale, 2 EXPs higher than me (obviously since I had no upgrade request in prior to check-in).

The AC lady switched my upgrade preference to using the SWU and then said I was first on the list. So it seemed the SWU trumps X at the airport. I think this is something known by people here, but needless to say, I wasn't assure of it.

I went to the gate at 5-10 minutes before scheduled boarding and inquired if I was still #1. The lady typed away for about a minute without any update. Then she called her friend over and said something about the 'N fare bucket' and a one-way. She said it was too early to tell, but that I was on the list. She wouldn't give me any further information, and AUS doesn't have the screen displays which show the list.

Boarding started and then my name was called, and it's 'X' inventory. Historically my SWUs have not been X. So I wonder if it was too difficult to process and she passed the other 2 EXPs higher than me and just put me through on X for ease of operation. This would then show how easy it is for a gate agent to be selective on who gets what at boarding time.

Anyways, worked out for me, it does seem SWU trumps Comp at least under airport control if you work the problem.

Furthermore, at 100 hours, there were 7 seats for sale (not using Expertflier, but just checking seats available from aa.com). I know this isn't absolute, but throughout the 100 hour period, seats were getting picked off one by one until there were 3 last night before going to bed. Then this morning there is only 1 available when on airport standby. So it still begs the question, did any of those seats go to EXPs flying X? I have to imagine so. However, my ticket was purchased less than 1 week out, so my situation probably wouldn't have worked out either way.

Anyways, thought I'd share, but definitely it seems you need to work the problem with SWU domestic legs once it goes onto airport control, mine didn't roll over and it seems it was the difference between an upgrade and not (although processed as x).

Cheers,
Brian