While I agree that the lack of waitlisting and CDYB limitations make this less useful, I'm not sure about the subset comment. Most airlines only have one inventory bucket for upgrades and I am not sure that their systems could differentiate seats for *A upgrades and their own upgrades. Consider that when UA had special 1K award inventory, they actually had a separate inventory bucket. Now, it could be like the award situation for *A that does seem to limit awards based on carrier, but nobody has actually confirmed this from a reliable source. The upgrades may work off *Net and that could potentially limit the upgrades using MP miles on some carriers (while the carrier allows their own members to upgrade). Bottom line is that you are assuming the upgrade inventory for *A awards is separate from the airlines' own members.