I dont agree that Maya software renderer is used for previews only...its also strong renderer if you know how to use it,unlike the mental ray where everything is done for you by calculating photons path,Maya software asks for more adjustments,and more faking!
Mental Ray is pritty slow but it gives great resaults and I only use it when extra realsitic render is needed!
The real power lies in shading network and knowlage to manipulate it and different renderer will give different resault!
Blury Reflactions and Refractions can easly be handled in Mental Ray.
You have an attribute in each shader that gives specularity under Mental Ray extention you can find these attribs!