The light intensity in the Stingray PBS material is measured in light stops to match the lighting calculations of the Stingray game engine. As a result, the same light intensity appears a lot more bright for Stingray PBS materials than it does for Maya shaders.
If you are only planning to use this shader inside Maya and do not plan to export the shading network to the Stingray game engine, you can disable the Light Intensity in Stops option. In the Stingray PBS node Attribute Editor, click Open ShaderFX, then select the Stingray Standard Base node in the ShaderFX editor, and disable the Light Intensity in Stops option in its Attribute Editor.