In the bowl of an electric mixer fitted with the paddle attachment, combine all purpose flour, whole wheat flour, oats, baking powder, sugar, and salt. Blend the butter in at the lowest speed, and mix until butter is in pea-size pieces. Lightly beat 4 eggs. Combine buttermilk, 1/2 cup maple syrup, and beaten eggs. Add to flour mixture. Mix until just blended. The dough may be sticky.
Dump dough out onto a well-floured surface, and be sure it is combied, knead gently if needed but be careful not to over mix. Roll dough out to 3/4 inch to 1 inch thickness with a well-floured rolling pin. (there will be lumps of butter in dough.) Cut in 3-inch rounds with plain or fluted cutter, and place on a prepared baking sheet.
Lightly beat remaining egg with milk or 1 tablespoon water. Brush tops of scones with egg mixture. Bake until tops are crisp and insides are done, 20-25 minutes. Remove baking sheet to wire rack to cool for 5 minutes.
Make a glaze by combining confectioners sugar, remaining 1/2 cup maple syrup, and vanilla. Drizzle each scone with 1 tablespoon glaze. Sprinkle with a little uncooked oats if desired.