Their website team (in USA) finally posted to Facebook the following message:
We are grateful for all your (many!) messages of concern as you learn about the impact of Hurricane Irma on St. Martin.
At this time electricity, internet and telephone are not available and we are uncertain when the team at Grand Case will be able to communicate with all of us.
Please continue to keep Steve and the amazing team at GCBC - as well as all those who have been impacted by the hurricane - in your thoughts and prayers.
As soon as we are able to provide an update we will do so.
-- Nevin and the website team standing by on the North American mainland.
Also, I think you can kind of see some of the buildings in the background of some of the photos Calmos cafe posted. Otherwise, i haven't heard anything "verified".