Inducedrag,
Our AIMS system has never worked properly with Safari on the Mac. Sometimes, a beta version of the next version of Safari has worked, but stopped once the release version appears. Now, it won't even work with the betas.
Firefox for the Mac works in every way on our company's AIMS system except for the Vacation Bidding page. You can see your vacation, select days to book leave, but the button to submit the days doesn't work. It's ludicrous. I ended up doing it at work, rather than home.
The Opera browser works as well.
Applemacster.