The add-on works great!
I love the AMPbot that is running from the developers website which crawls your AMP pages for errors and gives you tips to enhance the add-on. Works way better then the GSC.
The support is in one word excellent.
We use a custom add-on and AMP didn't work there. The developer asked me about that add-on before I got to it and after some testing AMP was working great there too.
It's not cheap for larger forums but well worth the money! Earn itself back