Having just made the leap to Sierra (10.12.2), I've discovered that one of my favorite add-ons is behaving funkily, and wonder if any of you have discovered an alternative.
I don't actually care that much about Growl itself, but Hardware Growler is a wonderful add-on to Growl that gives you all sorts of info about what's going on behind the scenes with the hardware you connect/disconnect from it. Everything from USB, Bluetooth & Firewire to Network, Power and Volume mounting/unmounting.
Since it's primarily just reporting things that system doing & noticing, I would imagine there might be something like an Automator workflow, integrated with some command line tools that could replace it?
I'm using version 2.1.3 of Growl, which is the latest, and what I was using in El Capitan. HardwareGrowler is at version 2.2, and again, that's what I have been using for quite some time.