Veeam Backup Free has its main limit in the fact you cannot schedule backups, more than tha 1 VM limit (that is per job, you can backup all your 6 VM one at a time).
On the other hand, Veeam offers both backup and replication to a remote ESXi server with a datastore attached to it, even a free one, since it's licensed only for the source hosts it takes backups from. And it can restore both the entire VM or single files from a single backup.
They have a 30 days trial, maybe you would give it a spin to first of all find out if it can fit your needs.
Luca.