Postgree is the most amazing DB, even more it will be the only one that will remain free (the good ones) as MySQL has been taken. In order to move on with this project, as an Java Senior Architect, I am recomming to you guys to have an special "Section" for Audit tables. As we separate sequence in another seq, we should do the same for Audit tables. They have their own behavior, are less used, and so on. I got in the mailing list and am sending the email just to give this idea for you guys, keep in mind and implement as you want.
Regards.