Hi Robert, right now I don't have any immediate plans for supporting Rhino v6 .3dm files. It might be possible in the future, but there seems to have been a lot of changes in the OpenNURBS toolkit for version 6 and so there could be a fair amount of work involved in supporting Rhino v6.

Blocks/instances are something that are high on my radar though for MoI although they won't be done for MoI v4.

For now to export from Rhino v6 to MoI you need to choose the Rhino v5 format .3dm when you do a "Save As" out from Rhino.

- Michael