I record Good Eats programs for later and just got to the one on Standing Rib Roast. Alton uses a terracotta pot on a terracotta base because the dirty oven would not focus the heat well and one side of the roast would cook more than another. There are other programs where he uses techniques like that.
What about "convection roast" though? We just bought a spiffy Bosch oven with that feature and I assumed that the convection part pretty much eliminated hot and cool spots. We've got convection bake and convection broil, as well. Isn't that what it's all about?