Euhm, vSphere HA does not replicate a VM. It just restarts a VM after a failure has occured. FT is what "replicates" a VM on another hosts, literally a mirror both from a compute and storage point of view.
With vSphere Replication you can also replicate within a site to a different device, it will provide you extra availability in this scenario... if your NFS device fails and the other is up and running you could failover.