we did run into some issues that I don't currently recall. Having said that - we actually recommend to use 8.3.x or even 8.4 as those contain a lot of improvements.
May I ask for the reason that you want to use 8.1?
I need to install Jopr Server on a server that has already installed Postgres 8.1, and many other applications are using this database. I donÂ´t want to upgrade the database because has other applications data.