although AltaVault is indeed a great appliance, i think the issue is still going to be how to get the backups to it, currently we can't natively Mirror or Vault from a FAS controller to an AV box - unless i've missed that announcement.
Alta Vault is also available as a HyperV VM as well as an Azure appliance - but the question will be how to get the data across - in a future release (disclaimer, this may or may not happen! 🙂 ) you would be able to use SMHV to do the backups, vault these out to Alta Vault and this will then send them off to a cloud repository of your choice...
but not there right now, as i say, unless i missed something...