I would beg to differ with you regarding the term refining whose definition includes the terms purification, filtering, processing and distilliing. So by definition, the reduction of sap to syrup IS a "refining process".
The grade of maple syrup used in The Master Cleanse (Grade B) is made closer to the end of the season when the Sugar content is somewhat lower, when refined/reduced/processed/purified etc, it is darker in color, has stronger maple flavor and though I would never call maple syrup a power house of nutrients, it is more nutrient dense than the lighter grade A.
And purely from a taste standpoint, the Grade B is far superior to the Grade A Amber or even the dark Amber. Not to mention the fact that it is somewhat cheaper.