I have been observing the upgrade clearance on my regular two flights to see what my chances will be as I move up the ranks and here is what I have observed so far.
On my outbound Monday 545a SEA-CLT I am seeing upgrade chances being pretty good. I sometimes see a blank upgrade list and my one time as a Plat with e500s I was able to clear into the last seat available.
For my Thursday 4:30p CLT-SEA, it is much harder. I sometimes see Group 2 boarders so some Plat Pros did not clear into First, Group 1. On most of my Plat e500 attempts I am in 1st - 3rd on the list but I see J0 usually in the morning already. I did clear once as a Plat with e500s but have made about 4 attempts so far. I do think that when I hit Plat Pro in a few weeks that I will have a good chance on the outbound and maybe a 25-30% chance on the return. That may improve further after summer.

I am still cursing AA for not allowing any status matching or a challenge beyond Plat. It has been a long hard climb up the ranks to catch up to my granted Plat status and then exceed. I haven't had to do that climb since I became a UA regular in 2005.