I should have kept reading that article before posting. <Apologies> Seems that a mask is a mask is a mask and that, "The black portions of the mask are completely protected and no sharpening will be applied in these areas." Now I know. Thanks all.
Masking in Raw refers to the sharpening effect being blended. It takes a zoomed view to notice the difference to the image with ease. In typical usage of this feature your only adding a minor amount of sharpening and then around halfway point of masking. Overmasking will counter the effect you applied with Sharpening for the most part as the edges are usually what you want to sharpen and the more you mask the more concentrated the mask becomes on the edges of the image! Hope that helps!