Yes my editor is collaborative :-) Unfortunately, non-square grids - such as hex grids - are unlikely to happen. Although I initially intended for it to be grid-agnostic, at some point I kind of gave up and now a bunch of features rely on the square grid to work. Changing it now will involve a lot of effort, and honestly I prefer to spend my time improving the current editing capabilities than introducing new grids.
All that said it's open-source and the parts responsible for the collaboration *are* grid-agnostic, so you're welcome to give it a shot :-)