Harry,
You probably want some sort of Word import facility in case you are sitting on a pile of documents that you want to convert/upload.
With 300 users, you'll have a mix of people who prefer WYSIWYG and no doubt the IT gang would use Markdown. The biggest thing with WYSIWYG is cross-browser cut-past screenshots -- make documenting as easy as possible.
Pages tend to lead you down a path of N-clicking before you get down to the information you need (nested pages of N depth). Some people prefer classic single document view -- just scroll to consume the contents.
Folders/Space/Collections will need to be augmented by tagging of some sort to help organize content -- no point typing up know-how if nobody knows it exists.
You always get teams that want to ring-fence their content so team, global and personal content visibility is important.
Feedback/actions tend to still rely on email tennis so look for something that handles the basic workflows to ease the burden on content owners.
You should add https://documize.com to your shortlist (started this to solve the docs+wiki problem).
Hope this helps you.
We have already started doing this @ Documize.
The app is built in Go (front-end back-end) with a some Java libs that will be converted over time into Go.
Handles .DOC and .DOCX today. We have put a tonne of work into handling the nightmare of a format that is full of surprises at every turn!
We plan to open-source the document conversion library once fully converted to Go. No ETA yet as we only went live last Friday.
If you need diagramming, Markdown, WYSIWYG, Jira/Trello integration AND versioning, revisions, approvals lifecycle, then maybe Documize can help you.
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