So I am planning to move my MariaDB service over to a separate instance as opposed to my current setup with all the services in one server. I am not entirely sure about the pros and cons and a total noob when it comes to server management.
This site is running a separate MySQL server and Webserver. The main reason was the resource allocation for price. You actually get slightly more RAM, and an additional CPU core running 2 instances, rather than a single VPS.
An additional factor to consider, is the network connectivity between the two instances. Any latency over that will be added to every database call made.