In typical cases the IFC export function of Revit should be satisfactory and provide adequate options for the export of IFC from Revit. Geometry Gym do provide an enhanced exporter through the Export IFC Enhanced button which provides some further bespoke features not available in the out of the box Exporter.
By checking the IFC4 option the model will be exported in the most up to date version of the IFC version 4 format.
By checking Structural Analysis the Revit defined analytical model will be written to the IFC file. This can be used to transfer models easily to structural analysis applications.