The reason for it not being supported is that 2012 wasn't released at the time of CMS 5 R2 and could not be included in the testing.
But EPiServer isn't using any special types in the database so running it on 2012 should work fine. But yes one issue is that it isn't supported so getting support for eventual issues might be hard.
Got a question from one of our clients, who's currently running a EPiServer CMS 5 R2 SP2 install, wanting to upgrade their SQL server version to 2012. (CMS upgrade in later phase).
Anybody got experience with running SQL 2012 and CMS 5 R2?
Is it stable? Potential issues? Does anyone recommend?
Thanks in advance.