I've been baking two loaves at a time, one in a cast-iron Dutch oven (4 quarts, deep bottom), the other in a cast-iron combo-cooker (3.2 quarts, shallow bottom), and the loaf in the combo-cooker seems to cook faster and darker.
I preheat the oven at 475°F for about 50 minutes, bake covered 30 minutes, finish uncovered 20 minutes. During the preheat, I use an oven thermometer to gauge when my cast-iron cookware is up to temp, and I've noticed some variation depending on whether I place the thermometer in the Dutch oven or in the combo-cooker, and where I place the lids.
The combo-cooker has less mass than the Dutch oven, so it preheats faster, and I suspect this plays a part in the difference in the finished loaves. I might try putting the combo-cooker into the preheating oven a few minutes after the Dutch oven to try and even things out.
What sort of preheating arrangements have people found to work well when using a combo-cooker? Lid on, lid off, no preheat, lid-only preheat, etc.?
For context, I'm working through the recipes in Ken Forkish's Flour, Water, Salt, Yeast.