I'm going to throw a while guess here...No.
Think about it: If you were making the same beer with extract, the majority of your flavor would come from steeping the specially grains (at least a majority of the flavor from grain, as oppose to hops/yeast/etc)
Most specialty grains are steeped, not mashed. Meaning that they would be unaffected by the efficiency of the mash, and contribute nothing to the OG. So you would end up with the same amount of flavor compounds, plus more sugar (maltos, etc) from the increased efficiency.
So by that logic, if you want to decrease the grain, while retaining the same flavor, you should decrease the base grain and leave the specialty grains the same.