Have you considered Data Recovery or Veeam Backup ?
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This is a cheap-o method, but we primarily leverage third party backup agents (Microsoft Data Protection Manager) inside the VM guests.
If you already use 3rd party backup, why are you concerned with VCB? That's the product, not the API. If your 3rd party fully supports the VCB API, that's all you need to backup. Agents are not a good idea for VM's, but you aren't using VCB to begin with.
Or use VDR that's still "cheap-o". VDR doesn't use VCB AT ALL.
I've considered both Veeam's product and the new vDR solution that VMware provides. Both would incur additional licensing costs (we run vSphere Standard Edition), maybe not too much... but since the previous solution (VCB) was included in the package, I'm still weighing all (including free) options.
Also, to clarify a little about our backup strategy - we use VCB as a secondary means of backing up certain critical VMs. The backups are taken once a month, and just serve as a "second" option in situations where we either need to restore a full VM or in some cases deploy a clone for testing purposes (yes, I could clone the VM as well, which I do utilize in some cases). Our primary solution for system backups is Microsoft Data Protection Manager, which has never provided support for VCB integration.