Yup, I've used ion2 → ion3 → notion pretty much exclusively for 10 or 11 years now. I don't think I could switch to another wm for my main interface if I wanted to. But why would I want to? Gimp was the only slightly-annoying thing, and now that has a single-window mode.

I have only one feature request that I haven't figured out how to do myself: I want to hide the status bar (mod_statusbar) on certain workspaces (the ones that have a full-screen browser). Anyone have any ideas?

Yep. It's remarkably stable and gets so many things right. I recommended it in my recent post on why you should try a tiling window manager:

http://adereth.github.io/blog/2013/10/02/why-you-should-try-...

Has anyone kept up with notion development?

I use notion, and will be for the foreseeable future. I suspect the article skipped it because it's in nonfree on Debian. This is due to Tuomo's funny licensing, and I don't think putting it there is fully justified, TBH. As for the development, there have been various bug fixes and some minor feature updates. It was and still is a fantastic WM

Wow I thought I was the only person still loving ion3 and notion. Notion has a few nice updates. Needs much more love.

Count one more - I also use it all the time when working under Linux. Haven't found anything close to it.

Nothing much [1] but it works fine. I use it everyday.

[1] http://notion.sourceforge.net/#changes