I just commented on this in the BF thread. It’s fast and lightweight, leverages QuickLook for reading any file the Mac/iOS can, and doesn’t require docs to sit in a proprietary database. It doesn’t do as much as DevonThink (which I own) but it’s very fast and seems to work well.
I currently use EagleFiler on my Mac, and don’t have a cross-platform solution so I’m slowly evaluating it as such, but I’m generally reluctant because I like EagleFiler (which it resembles) so much.
When I first launched it I simply set as my app’s ‘home’ folder my 30Gb+ Documents folder, and it loaded almost immediately, effectively turning it into a Finder replacement where I could also edit files.
Here’s an example of some sub-sub-folder action, as seen by the Mac Notebooks app, using my customized choice of font and background colors:
