Hi anyone have any experience with either ?
You can use anyone of them. If you wants to use unlimited space for EPPM then go for SQL server enterprise edition and if it would be less than 4 GB than go for express edition.
In my view.
For p6 EPPM 8.3 installation, you can go with Oracle database because for sql server we need to do some extra steps comparing to oracle database for primavera installation.
I'm curious as to your reply, in my view an Oracle database has more extra-steps.
For sql server the only extra step I can think you are referring to is to add the 'set DATEFORMAT ymd' parameter in the admin app.
If you go the Oracle route you will have to install the Oracle Client on every sever or end-user workstation that will be talking to the database where as sql server will connect 'out-of-the-box' (assuming Windows servers/desktops)
Oracle DB certainly has advantages in scalability where-as SQL Server is easier to deploy without needing to retain a DBA.
Side Note - if you plan to deploy P6 Analytics - definitely go with Oracle to avoid having to use a Database Gateway.