In my opinion, much more important than the GI-GR dilemma, is to use an image-based lighting scheme. And mind, it does not necessarily have to be an HDRI to produce good results. If the photograph is good and properly made, even a normal photograph can produce very good results. Attached is a test scene I made using a photograph of mine. What you see is an "environment" (i.e. IBL) scene that uses my photo as source and the DEFAULT values (yes, default! No need to tweak sky illumination). GR is used but I tested GI and it gave a practically identical results. Both GI and GR were very fast with this scene. Rener mode is Superior. Orio