Conceptually there is no numerical reasons why you would experience any problems. The scaling characteristic was a common method used to build photonic crystals before they could be built in the correct scale.
That being said it will depend on the desired simulation. If it is simply propagation then there should be no problem. If your colleague wishes to fully model the source using currents or to model currents induced within structures then this is something that the product does not natively support and would require some additional pre or post processing.
Scott