What is the best method for establishing a clone/test copy of our site?

Hello!

We have a multisite installation with only one site currently installed. It is on a VPS and installed under it's own cPanel. I need a copy of the site for testing plugins, modifications, and updates.

I've read what seem like complex scenarios with Snapshot, and we own BackupBuddy but it claims to be "experimental" with Multisite.

I have WHM and root access, so if necessary I could copy the site to something like test.domain.com and even install a new CPanel for the test site if that simplified the process.

Can you offer a good method for copying the live site to a test site?

NOTE: If a particular plugin - even premium/paid - is excellent at this task, I'm open to considering the cost if it means an easier procedure.

Thank you!

James