Adam,
I run a pro cookie baking company and everything i want in my cookies...i want the exact opposite for my gingerbread...lol
i want my cookies soft and moist...my gingerbread hard and dry...so i reversed all the ingredients and got the dough recipe from that. the baking soda makes things flat...baking powder makes them puff.
so that's why the small amount of soda in the recipe. and yes it does help in browning. and you are exactly right...i wanted a light dough that could be colored easily and perfectly...hence the corn syrup and no molasses. this dough colors perfectly every time for me.
please let me add a trick for perfectly shaped pieces if i may.......i bake my pieces on foil for about 5-6 minutes, then remove from the oven and cut the doors, windows and around the outside edges. you have to do this fast as the dough hardens quickly. i use the template and an oven mitt and pasta wheel. then the pieces don't spread any more and are perfectly square around the edges. they are baked just long enough to keep their shape. then i finish baking, flatten between paper towels and books overnight, and viola! flat, hard, smooth pieces that go together so easily. no fudging with icing. and i apply everything including gumpaste and fondant and it never falls off.
hope this may help!!