Nice! I've used this technique a bunch; it's great for reducing your light signature, and, as you mentioned, for producing less smoke. You can also slide a flat rock partway over the main hole as a cooking surface. Good job on the demo!
Lets not for get about the advantages of fire control and quickness of extinguishment!
Another thing to think about and I learned this the hard way... still setting up rocks around the hole. Not only can you gain from the heat of the rocks (if needed) but it helps you from stepping into or slipping into the hole if not paying attention!
This is a pretty slick technique. I tried it out on my last trek and it worked wonderfully but it was time intensive due to the soil being fairly hard (did a number on my shovel). To save time I dug a trough out for the chimney then used large sticks to keep the shape as I filled earth in over it. This does make a much more noticeable footprint though. As it was I spent almost an hour building my first one and only really plan on using the Dakota Fire Hole for camps that I plan ton stay at for longer than one night or in locations with softer ground.