on projects where i ended up selecting oracle, *my* main reasons were (1) clustering/replication (2) cross-database query (3) promise of drcp in that order
for (1), actually more for synchronization/transfer, i got a simple suggestion: while installing postgresql, why not ask the user to give ip of a 2nd remote machine with the right ports open on which the installer can then repeat the exact installation, prompt for sync frequency, and do a pg_dumpall/pg_restore based on that frequency. so by the time you are done installing, you got a "stand-by"! repeat that for upgrades. it is easy to do manually (setup cron, navicat etc) but far easier when combined during postgresql installation.
