Have to disagree with the original premise. Sure, it's getting more difficult to upgrade my BOS-SFO trips (see below), but CR-1's are what keep me from jumping ship to AA. I get 8 CR-1's and 6 SWU as a 1K. AA would only give me 8 SWU-equivalents as a 1K equivalent. That's a huge difference.
I am currently EXP and not long ago was 1K, based in BOS. I think you're better off on AA unless you can consistently plan far enough ahead to get confirmed upgrades with your CR-1s (I was never able to do this). AA does not limit the upgrades, and while BOS-SFO is a tough upgrade on both airlines, my experience has been that shorter flights are much, much easier on AA as EXP than they were on UA as 1K (mostly due, I think, to the larger number of F seats on most planes).
I would also argue that 8 VIPs (AA equivalent of SWUs) are more valuable than 6 SWUs, if you travel enough internationally to make use of all 8 (given that there is no need for a CR-1 equivalent on AA unless you are able to confirm CR-1s in advance).