I have been using HG for years and it's fine. The only issue that I'm really concerned about is the programming of custom scripts. HG works, but the way you reference modules is not intuitive. I don't know how HA and Domoticz do it, but HG is NOT like AHP API. In the AHP approach you wait for a triggered event and respond. In HG, the code can be triggered by timed events or value changes (sensors, modules, etc) however, you have to loop through everything in the system to figure out which event triggered it. Unless Gene changed things since I wrote my Advanced Smart Lights code, it's NOT intuitive.
IOW, it is possible to do almost anything you want with HG in code, but the way you get there is not conducive to new people coming in and writing their own code. In other languages you can have pseudo code and convert it to real code very quickly. With HG, you can use the pseudo code as a guide, but it can't be executed in that order necessarily.