I have a tagine and I love it! But mine is glazed terracotta clay. Before I bought it I did some reading and found Paula Wolfert, who apparently is the acclaimed expert on the topic of Moroccan cooking. (She has lots of credentials if it means anything to you).
She says that she used to tell people that a dutch oven served the same purpose as a tagine, but learned that the flavors develop more in the traditional vessel. She also said that cast iron is less than ideal. It has to do with the way the top stays cool and condenses the vapors, basting the food as it cooks. In an enameled dutch oven, the food braises or steams, which is different. The top of a earthenware tagine stays cool during the cooking process.
I have no experience with the LeCreuset, as I took her advice, even though the enameled ones were pretty. Mine is 2 quarts, which is ample if you're cooking for 2-4 people. It's not a braise, and you don't need all that liquid, so the pan is shallower than a dutch oven. The diameter is about the same as my 5 quart dutch oven.
I had tried several North African recipes, with varying success, but once I bought the tagine, my success rate soared. One of my favorites is short ribs with dates, prunes & olives. Another is chicken with apricots, dates, almonds & preserved lemons.