Very cool. I am going to have to order one of these today. Is that one you linked to what your using?
Yeah I use the Lodge Color, they are great for the price, and I think mine is 6 QT. Basically just make sure it's enameled cast iron, as they sell non enameled, plain cast iron dutch ovens that you could say, use over a fire.
You can really go nuts with like a Le Creuset, or a Staub, but doubt they are really worth it. If the enamel chips on your dutch oven, I'd rather it be on a cheaper one, but that's just me. Although Lodge doesn't offer them, some other brands have oval sizes as well.
Also you'll often also see them sold as 'French Ovens'. There is no difference between them, from what I understand the French just hate the Dutch. You'll see that with Le Creuset, them being a French company.