The DOpus file find works perfectly well, with one note.
If you're doing a "content" find, you get a list of files that match, which is good, BUT what would be incredibly useful at that point is a "context" view of the found information.
I've used a tool called "Agent Ransack" to do file finds for years, because it supports that very notion.
You get a list of files, all well and good, but when you click on a file, you have a second pane that shows the found text, with context of a few lines before and after (configurable, of course).
Makes the file find (when you're searching for content and not just filenames), far more useful.