I agree with my Australian KettlePizza compatriot. It is not for sustained pizza production. But I am pretty sure you can whack out 3 superior pizzas from one load of charcoal and wood. Superior in the sense that they are made at home without the benefit of an expensive oven, either brick or other material. Hitting 700 degrees is very do-able and that will turn out a pretty decent pizza. Not world class, money is of little concern, pizza. Nor one steeped in decades of custom, perhaps even centuries of tradition.
I have heard of other pizza makers, with nice hot brick ovens lifting their pizzas toward the ceiling to give the toppings the benefit of the higher heat up there for a few seconds before pulling. Like any approach to good food, it is a balance of ingredients, technique, and equipment. A few folks are like Heston B., in search of perfection, others are in their backyard trying to do the best they can with what can be readily brought to hand.
I own the older style KettlePizza insert and I will differ here with synaesthesia on preference for the newer lowered version. I plan to put a lowered ceiling in mine within two months. I will have a heavier steel center, where I will park a quarter or half load of charcoal (Weber Charcoal Chimney = 1 load). The newest reviews of the KettlePizza over at the Slice include using a "pizza steel" for the ceiling. I respect Kenji, he's good and when he isn't he borrows from the best, a rather common practice among top chefs. The use of a steel has been incorporated, with somewhat different approaches, by Heston Bleumenthol, later seen mentioned by Kenji, but Heston did acknowledge McGee (I think) for describing it previously. And as long as we are speaking of Kenji, I thought he waxed rather enthusiastic about the new PizzaKettle, with appropriate hacks, rather than disparaging it.
But as synaesthesia says, its is finding how to use your equipment to produce the best product you can. If we were talking commercial endeavors, then the Weber/KettlePizza approach would likely fail. If however, we are talking about someone starting a journey of personal growth and experience, I highly recommend one for the beginning pizza cook wanting to start at home.
I can say that even the first pizzas we produced, far from perfect, had a great flavor. They benefited from being cooked in a much hotter oven than my indoor kitchen can produce. They were better than what we buy from either the local pizza shops or the international chains here in the Philippines. As I can, I control more and more of the ingredients. I can't do much about the flour, we simply do not have choices available to many in other countries. Our mozzarella is not top quality Italian buffalo mozz, but we make it ourselves, improving it when and where we can over the packaged stuff in the store. We do our own fresh sausages and smoked bacon, though we don't do pepperoni or air dried sausages - those we buy imported. And I find the KettlePizza a great way to start getting more serious about my pizza. I highly recommend it for those starting on the pizza path that enjoy experimenting and growing.