As per my understanding, Frappe is not truly taking the full advantages of ORM, and it only focus on MariaDB. We will not be able to use MySQL or Percona, which are very much similar as Percona is direct replacement of MySQL, and same is for MariaDB.
Percona supports encryption at rest. Will be nice if we are able to use it.
How much MariaDB specific things are used, and if we avoid that and only uses ORM way of things, will that cause many side-effects which over-weight the benefit of using any database for the backend?