Shaders are always in use - they are what tell the renderer how the lights and cameras work, and how surfaces behave. The alternative shaders have different features, and to an extent are redundant (both uberSurface and the AoA SSS shader offer sub-surface scattering, as does the default DAZ Shader with very limited options, for example - uberSurface/Human Surface Shader was an improvement over the base shader for some surface types, and the AoA SSS shader is an improvement over that in some respects though they have somewhat different features. Generally items will already have a good shader applied, at least to achieve the look the designer wanted; content imported from Poser or OBJ will not be optimised, and you may want to switch shaders around or at least tweak their settings (in the Surfaces pane) to make items from different makers look harmonious but it isn't something you must grapple with, especially if you are suing content set up for DS.