Here is the official IntelliJ support info. IntelliJ development support in 2.3.9 firmware update
IntelliJ has built in groovy support and really helps keep your code formatted nice by indenting as you go, etc... I found it works pretty good with apps code. The publishing to the hub is instant so it must be using something better than the VSCode plugin (probably new API for 2.3.9). However with drivers there are so many custom methods and functions it gets angry about them which is distracting.
I was/am using the tunnel feature in VSCode and I have not figured out how to do something similar with IntelliJ. So for now I have stuck to VSCode with the user plugin. I have IntelliJ setup on my code "server" to play around with but normally use VSCode from a remote machine.
