Dave, these kinds of ovens don't have thermostats, they have wishostats. It's a little like taking a Ford focus and putting a speedometer in it that goes to 250 mi./h.– no matter what the speedometer says, a focus isn't hitting that speed. Even if this oven can reach 400C, it's both going to take a long time to get there, as well as take a long time to recover between bakes.
Members have purchased these kinds of ovens, tinkered with them, and successfully made one or two pies at a time, but with your aspirations, I don't think this particular oven is the answer. If, say, this oven could bake a pizza in 5 min., but then require 15 min. to recover, would a pizza every 20 min. work for your schedule?
I'm not necessarily saying that it will require 15 min. of recovery time, but, with this kind of wattage, it's quite possible.