I've considered how to avoid backing up the same info multiple times. For instance, if you back up the databases to a backup file, you still want to be able to reconstruct the VM quickly, hence why I've converted all my servers to VMs. Backing up the databases to a VMDK that is marked as Independent Persistent is one way to avoid backing up the same data you otherwise back up.
That being said, it probably isn't the best way. For my environment, I have one big SQL server and I back up the databases using CommVault's SQL agent daily, then back up the entire VM once a week. On my smaller database servers I just backup to disk and back up the VM nightly.
I have considered how I would re-architect things when I make the leap toward replication, though. It would save a lot of inter-site bandwidth to avoid replicating both the VM and the database backups. When I get to that point I think I'll probably backup the databases to a network share instead of local disk for these small database servers (less than 100GB each).
For SQL Server versions 2005 and newer, backing up the VM and relying on VSS to make that backup consistent has never given me any trouble in 4 years. You're mileage may vary, but in most of my systems I no longer need to back up the databases to a file, I merely back up the entire VM and recovery is a 1-step process instead of several steps.