I would rate it eight out of ten.

It is widely scalable. It is as simple as plugging in additional hard drives into the server and adding storage space up to its capacity.  The software license is independent of hardware and is for Unlimited storage, so you can replace the entire storage server and use the same software license.  It can run on your virtualization hosts for a hyperconverged environment or on standalone servers.  There is even a free version with full functionality.

In each of the eight sites our company deals with, there are around 50 users, meaning there are around 400 people who use StarWind Storage Appliance.

In terms of scalability, StarWind software excels when it comes to a two-node configuration. You can indeed have multiple nodes, but the pairing typically occurs between two nodes at a time. If you need to expand your storage capacity, you can achieve this by adding two more nodes, whether they are storage nodes or compute nodes. This provides flexibility because if you only require additional storage, you can essentially purchase two servers with the necessary amount of RAM to run the VSA, and then you can allocate this added storage to the existing compute nodes in your production environment.

I work with environments ranging from 10 to 500 users.

Scalability is not an issue, depending on the hardware you have it the scale really fast.

We have only measured scalability currently with two servers.

This solution is scalable, but our use case is in the lower end of the market. We are in the SMB market.