Wiki vs. Bulletin: I am not completely sold on idea to have bulletin system for Knowledge Management. Generally speaking, if everyone is familiar common location in a hierarchy, it is easy to reference something. Searching, you may not recall the exact word or key word needed, but you’ll know the location. I look toward analogy of having an index vs. sleuthing through lot of information to extract the exact information you need.
Confluence wiki vs. Other Wiki: I am open to using an alternative code-friendly wiki, maybe something that can be integrate changes that occur with code, so that it is refreshed, e.g. https://www.mkdocs.org/.