DotSpatial.NetTopologySuite and DotSpatial.GeoAPI are supposed to be used with DotSpatial 2.0 that can be found on GitHub.
They are not meant to be used with older DotSpatial versions.
In DotSpatial 2.0 you should not have to use IGeometry.ToDotSpatial() because DS 2.0 uses the original geometries of DotSpatial.NetTopologySuite and DotSpatial.GeoAPI.
In case we overlooked something please explain more clearly what you are trying to do that results in your problem.
They are not meant to be used with older DotSpatial versions.
In DotSpatial 2.0 you should not have to use IGeometry.ToDotSpatial() because DS 2.0 uses the original geometries of DotSpatial.NetTopologySuite and DotSpatial.GeoAPI.
In case we overlooked something please explain more clearly what you are trying to do that results in your problem.