I've been working on the architecture of big Documentum installations, and I've experienced pros and cons of the whole stack in different places, starting from the Content Server, going through mid pieces like workflow engine or CAS storage, and finally opening the infinite box of web applications it has. But technical support guys have been always there, trying to help me when I've been stuck at any point.

Mainly for studies (design office) and construction (plans for mechanical components), e.g., responsible for documentation.