Oh my oh my - this is getting interesting. The GI actually is a big improvement in this scene. I"m noticing so many differences that are meaningful. 

Could you do more? If done right, then bright "sunlight" coming in the window should light everything in the room. You probably have to raise the infinite light so much that it blows out on the directly lit things, but that happens in real life too when you set you shutter speed and aperture to pick up the indirectly lit elements of the scene.