How can you give us Active Directory for free? Isn't this Microsoft's® bread and butter, the heart of Windows® Server? What's the catch?
Microsoft® does not own the technologies on which Active Directory is built (Kerberos, DNS, SMB/CIFS, LDAP...). It only uses them, as does Samba, the Linux implementation of AD.
The catch, if any, is that you do not always get the newest and shiniest features introduced in the latest version of AD. But, as a midsize business you probably would not use these features anyway, and the newest features are often what break and pass away.
What matters are core functionalities and security which are guaranteed by the fact that Samba is here to stay,* interoperable with Microsoft® AD, and used or supported by a large number of organizations. (It is offered as a cloud service by Amazon® Workspaces.)
What you get with Samba is a rock-solid Domain Controller that works with PC’s, Mac’s and Linux PC’s or servers and can be managed through a simple web interface. You do not have to use the clunky 20th century era Windows server UI.
Doing the right thing may seem harder at first, but in the end the TCO is much lower.
Whereas others would only know MS Active Directory, we also know Samba, and you get to benefit, for it is 100% free.
* Samba comes “pre-installed” in nearly all distributions of Linux as well as many versions of Unix.