Interesting thread. I took a look on every application mentioned here (even BOSWELL 
), but it seems to me that everything I could do with them I do already with Journler. Journler might have been intended to be a journal-keeping software, but I use it as a “throw-all-in-and-muddle-around-with-it”-application. It’s way of organizing items, to link anything to anything and it’s possibilities to search across all entries are amazing and really helpful.
DevonThink, however, is another category. Archive. Heavy-duty. I use it for fishing and hunting in my archive folders where I am collecting websites, PDFs and other material from the web and elsewhere since a dozen years ago, but then I copy and paste relevant material elsewhere - into Scrivener, into Journler, to a place where I will work with it. I don’t write in DevonThink (mostly because my Mac always almost breaks to his knees once I start it up; it is clearly the most demanding application I own).
I think AmberV is right: Every application is either to the side of being an archive (=dusty shelves in a cold cavern) or a workspace (=neat desk, paper available, fountain pen freshly filled).