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Just referencing the geometry would be fine.
Enhancement 822358 has been filed for this feature request.
Please note that referencing .rvt files (which can be very large) will probably be very slow, and require a lot of settings. It would be good to be able to set up an .ISM or i.Model type file that a Bentley user would be able to reference without complete conversion.
Same problem with .ifc files which can be referenced already, but very difficult to use... for large files.