maple flavor doesn't come from the sugar but from the minerals and non-fermentables. the whole taste is a combination of the sugar and these parts, so fermenting it will change how it is perceived, but you will still have a distinctly maple presence.
i've not done any experiments but i've heard that feeding the wort simple sugars once fermentation begins actually promotes higher attenuation than lower, since the yeast will not have access to as many simple sugars at first and will process a higher percentage of complex sugars before completely fermenting the simple ones.