I have been using this for a while, window managers that are configured via a language (xmonad, subtle, dwm) are awesome as they allow for you to customize the actions to no end.
Have you run into any problems? I’m very interested in Subtle but I’m using dwm currently. I’ve had a hard time switching from dwm since I feel dwm has few bugs and is relatively simple compared to most wms.
I still use xmonad on some computers, subtle doesn’t have the depth of snippets out there that dwm and xmonad have, but being configured with a proper programming language has made it easy to add functionality. In terms of stability, it has been fine, there are a few times when things kind of act up, but that is sometimes due to bugs in my config.