We carry two aluminum Dutches. A 10" and a 12". Neither have legs––but we almost always use them with coals. The 10" (4 quarts) nests in the 12" (six quarts). Both fit in the box that the 10 incher is sitting on in this pic:
To answer your question, I think a 10" Dutch is a bit tight for cooking a meal for two. When in doubt, the 12" is used. It's not good to have your Dutch filled to the top when you're loading coals on the lid.
I cut the legs off for storage reasons and so they can also be used on the stove, which is extra handy during cleanup. I use a Dutch oven lid stand for the legs when cooking with coals which is about 80% of the time:
From a cooking standpoint, cast aluminum dutches are equal to iron––or damn close. The downside is that they are spendy and don't strengthen your back muscles. I'd be hard pressed to revert back to iron.
Tony