Their team is fairly responsive to bugs but I had one negative experience when trying to help them fix their instantsearch lib. They were grabbing as many pages as you had set for max pages at once and would re query it on pagination - huge waste of data transfer. They refused to see the problem so I just did a private fork just to get it working but far as I know that’s still a bug.
I need to upgrade the engine itself but looks like they added the ability to upgrade and not lose all the data. That was frustrating but understandable.
Overall I’m very impressed how stable it is