High Memory Usage

The transition from MySQL to Maria is pretty seamless as they're virtually 100% compatible. As Jonathan said, it's a product of MySQL's original Devs and they purposefully made Maria an easy jump away from MySQL. If it does break something going back to MySQL shouldn't be an issue.
If you're interested in the compatibility issues, see here, but it's unlikely you're even using any of the incompatible features. Additionally cPanel supports the migration process along with MariaDB in general. See here for the migration process, but I'd recommend having KH do it for you if you're at all unsure. I wasn't aware KH was even supporting the transition, but from what I've seen Jonathan mention it seems they do.
Thanks @KH-Jonathan for the respond. I have some resellers on my VPS and I don't want to do anything that will break CMS/Forums that might be on some of these resellers accounts.

I wouldn't worry too much about that. I've never run into a situation where MariaDB broke something.
The lovely people at KH switched me from MySQL to MariaDB yesterday without any issues on my Wordpress sites.