Reasons to run Drupal on PostgreSQL What would be the strongest reasons for running Drupal on PostgreSQL, in terms of available features and performance? I.e. what postgres features of that are supported by Drupal are not available on mysql? For example, postgres is known for ACID conformance and transactions; does Drupal core take advantage of these or other features in any way?

This question is not about which is a better DB in general, rather whether there are any specific reasons why one might choose postgres over mysql. One obvious trade-off is that many contrib modules will be buggy running on postgres.

I am working with D6, but feel free to direct answers to any major version.
Personally, I think the only reason for choosing PostgreSQL over MySQL is if you (or your client) is already a PostgreSQL shop and have DBAs that know PostgreSQL well and know the ins-and-outs of babysitting it.  I would also say the same also applies for choosing MySQL over PostgreSQL, assuming you aren't using any contrib modules with MySQL-only functions in them.