One of the core issues we had when discussing FactGrid was, that there's an interest to integrate as much as possible of Wikidata into FactGrid but this will likely lead to having items inside the database that aren't well maintained.
One solution would be to have FactGrid give it's own items numbers like F1234. A statement that links to a new item could link either to FXXX or to QXXX. In any search for a new item all the FXXX items could simply be made to outrank the FXXX items. There could be a one-click way to copy a QXXX item into the FXXX namespace.
Native properties could go to the G namespace.
In the short term this is likely more development effort than writing bots to copy over specific information to FactGrid. More long-term it could however be very benefitial because it reduces data rod and a once developed extension could be used in the future also by other Wikibase installations.