Deployed V1000 appliance on dedicated ESXi hyper-visor. To evaluate I did backup of one of ESXi with ghettoVCB script - couple CentOS and Windows VMs. On first run it achieved total reduction of 3:1 (what was expected in our scenario). Consecutive runs raised to some 5:1. But backup time skyrocketed 10x times! compared to NFS server VM on the same hyper-visor with same conditions.
Leaving aside a hypothetical 15:1 reduction rate - as I can't go with that to stakeholders for business case justification in our case. For me it is no were to go with v1000 because of 10 times slower backups!