"The terra cotta pot is less about how clean your oven is, and more about proper heat distribution. those arrogant ones who say..."my oven is clean, I don't need it"...will see poor results. No oven keeps perfect heat, no matter how expensive or new or clean.
Second, here's an idea to help your probe. When it goes back in to "put the spurs to it" at 500 degrees, wrap the probe tight with foil. have lost may a probe this way.
This method is awesome, and Lowe's carries these pots in stock, year round.