Are Altium Vaults worth it for a small company?
I had to decide something similar years ago.

At that time, Altium were selling their Vault solution which can have several different configurations:


The Vault is in the Cloud: No internet access = no file access. If you don't continue with Altium and stop to pay the yearly subscription you don't have access to your data anymore. NOT ACCEPTABLE
The Vault is on a server in your company. The content is encrypted. In order to access the data, you have to identify yourself to the Altium web services which unlock the access to your own server. Drawback: If you don't continue with Altium and stop to pay the yearly subscription you don't have access to your own server data anymore. No internet access = no data access! NOT ACCEPTABLE
The Vault and the identification server are on a server in your company: your are 100% independent. That's good. This option was advertised, but during years Altium said that it's not available yet, or under test, but "soon" you will be able to have that.


Our conclusion was: If you want to be free, to be the only master of your data access, either you use the Vault on a custom server and you control everything, or you stick with SVN and forget all their stuff such as "unified design", "release management", etc...

If things have changed in between, feel free to update my answer with the latest conditions from Altium.

EDIT:

Things have changed in between!


None of the new options require internet access to use your Vault.
The data is never encrypted thus it is always possible to recover the data.
The license for the Vault is now perpetual and it is still working even in the case of stopping the "subscription program"
The authentication is not based on an Altium web server anymore.
The data is always stored inside your company and under your full control.
The release process in not fixed anymore and supports a lot of customization.
SVN or any version control system is used for the version control of your day to day work. The vault is only there to store your components and the released work.


Now there are two options:


The personal Vault solution: only one user, data is stored locally (in a local Vault), reduced functionality. But no additional licences are required.
The vault server. Several users, data is stored in the Vault server, all the functionalities.


In one word: It seems that they have heard the response of the market and fixed the major issues.