I had the same issue, but I switched from Karabiner to https://www.orderedbytes.com/controllermate/ and I couldn't be happier.

It did take a bit of extra time to replicate my Karabiner setup, however controllermate is much more capable and the overall result has been worth the effort.

Does it allow you to implement the conditional mapping of karabiner for capslock,i.e. By itsrlf its escape, with another key its ctrl? That's the one thing I've gotten so used to having that I don't know if I could go back. Im remembering now why I never did make the leap to Sierra.

This is the first I have heard of this app. What problems has it solved for you?

I regretted upgrading to Sierra because I lost my favorite functionality of Karabiner. But I got most of the features back when I started using Hammerspoon. It's not GUI friendly, but it's doable and there's a lot of scripts available. It's similar to Window's Autohotkey which I use at work, but Hammerspoon has a sane, real language (Lua).

My other suggestion is to actually replace keyboard. ErgoDox EZ and Ultimate Hacking Keyboard have almost all the features I need from Karabiner, but is saved to the firmware, so I can take the keyboard anywhere and it just works. Also, they're mechanical keyboard, so it's nice to type on.

I use Karabiner to remap all the keys/buttons on my Razer Naga (so I can avoid using Razer's awful software). I've looked into Hammerspoon but it's not clear if/how I can remap keys only from a specific device.

Is it possible to rebind the caps lock key? That's the only reason why I have Karabiner-Elements installed, using the caps lock key for delete_forward is the best thing ever.