Some discs are 3D only, some have 3D and 2D versions on the same disc. Whether or not a 3D only disc will look anywhere near as good as a 2D capable disc when played in 2D by turning 3D off, that I can't say. When you switch to 2D during the 3D disc, you're still using your 3D settings. You would have to alter your setting each time or use a different mode, etc. I'm also not sure if identical settings would look the same between normal and 3D modes.