PG 7.2.3 is the safe choice. While I did the work necessary to support PG 7.3.x for 4.6.2 I don't know of anyone who's tested it thoroughly in a production environment. And 7.3.0 had a bug in it that kept OpenACS from installing (7.3.1 and newer versions work fine.)
So all in all I'm fine with sticking with 7.2.3 for the reference platform while encouraging all of our developers and keyed-in avant garde users to use 7.3.x if at all possible (all my development the last four or so weeks have been on 7.3.x so indeed it does seem to work fine.)
