Thank the Readdle team for offering this great product.
I read on my iPad mini, sometimes iPhone, while I am on the train.
And read on my iPad HD at home.
It would make my life much easier if the annotations could be automatically synchronized across those devices.
If you are someone like me. Gracefully, there is a sync feature in PDF Expert that allows me to sync files through WebDav servers, and we can make better use of this feature to sync across different devices.
I made this short video to guide you through the configurations: