We were having issues with using a real wiki, which I think is not uncommon: hard to navigate, changes were opaque and unclear, stale data, hard to search, etc. etc.
So, we adopted a different approach. We now keep all canonical developer documentation as a series of Markdown files in a repo on GitHub. This means that:
It's been a year since we created ours and it's been working. It's not perfect, but it's a lot better than Confluence.
The main drawback is the inclusion of diagrams. We've been using a mixture of OmniGraffle (uploading the
.graffle file) and http://yuml.me. Using Gliffy in Confluence is way better, but it's a tradeoff.