I primarily used this solution for IT documentation and documenting ISMS based on ISO 27001.
With the Confluence Wiki, I implemented quite a series of successful IT and Security Documentation projects. Confluence was my preferred product when starting any collaboration project that had to produce comprehensive, centrally organized, and highly usable documentation.
I worked on several projects that implemented an ISMS, based on the ISO 27001 standard, which mandates a "documented ISMS". I introduced Confluence as the tool to be used for that documentation.
I used Confluence as the "self-hosted" server in VMs or on MiniPCs running Linux. I always added backup methods, so the HA functionality of the much more expensive "datacenter-edition" was never needed. The largest environment I worked in had 100+ active authors, but typically I would work with the 10- or 25-user license, which are both quite affordable even for small customers and where the server resources are manageable (From two to four virtual cores and 4-16GB RAM will do fine).