I have used a 2005 Publisher with a 2012 Subscriber. I think if you want to try a mix of SQL versions you should try it in a test environment if you are concerned about it not working.

The other info from BOL about versions that is related to this is that it indicates the Distributor must be at least as current as the Publisher. So, if you have a 2012 Publisher then the SQL instance hosting the Distributor needs to be at least 2012. I have not tested that info from BOL.