I have assisted various organizations to implement this product as well am currently using DataCore's SANsympnony product in my home lab and place of employment. We have 20 DataCore storage server across the enterprise, at 9 different locations with over 2 PBs of storage.
This solution allows the use of off-the-shelf hardware and charges by the TB of storage. So we can throw in our own enterprise-class hardware (including SSDs) and not pay any extra based on the type of storage we use. This is the same model used with server virtualization. Keep the hardware separate from software. This is true "storage virtualization" at its finest. The software over the years has matured to be very robust and allows you to build a very high performing storage platform. It has all the features of any high-end SAN such as fiber channel, iSCSI, thin provisioning, storage tiering, snapshots, continuous data protection/recovery synchronous and asynchronous mirroring, performance reporting/graphing, true HA design.