Sp, you still have this problem now or not?
I think, the most exciting idea would be to rewrite setup_mysql module for version 2 and postgres, but we are gonna change something serious in database (in the next version already, for example), so are not ready to support additional databases just because of NO TIME :-( I think, version 2 will be on the way soon, so for a while we will just support fixes in the main version and only then work on additional modules.
On our opinion, postgreSQL is also out of this list, because they are doing too many changes themselves now... different table structures in different versions etc. Mostly our users are using mySQL, mySQL is a leader, and we will better to support a leader else starter :-) We are starters, too... and already it is enough with mySQL for us. Just a question of time.