Doram
Hi there,
I used to use a very heavy round one which I think is iron covered enamel I got many moons ago from Sainsbury's (see picture) and although worked to a degree it got nowhere near as hot as the Challenger. Plus being round, it limited me to the shape of sourdough I could bake. In the challenger I've baked Boules, Baguettes, Rolls, Focaccia as well as bloomers.
One thing against the Challenger is the weight. Being made of solid iron...It is very heavy! Also, because it is solid iron it retains the heat for ages. You could bake a loaf and then after cook a steak in it with the remaining heat easy.
Oh, but another plus. I've also heard that because of the shape of the lid and the two handles on the top, people have turned the lid upside down and cooked in that too and the handles become feet.
Yes, there are other iron Dutch Ovens out there from different manufacturers and probably a fair bit cheaper but I hadn't seen one bad review on the Challenger and as you can see it is a bit more versatile than a standard round one. Regardless of the price, it is undoubtedly better than not using one... but then a Pyrex lid turned upside down on a baking steel or stone is better than nothing too, and of course a lot cheaper than the Challenger.
Like anything it's horses for courses and you get the best you can afford. Many people who don't use the Challenger have great success with their sourdough... me? I need all the help I can get 😉

