Best practice for Servers in Production

Hi,

We have 2 different environments with a SEPM in each environment. Both of them has got their own SQL Server which replicates with each other. They want to change the second environment to either SEPM and SQL on the same Server or embedded database on the one environment.

Does anyone know where I can find a best practice on why to use SQL and why on a seperate Server and not on the SEPM Server.

Thanks