Nick I think you were right, you can leave your B. autatum were she was.
B. auratum live in wet and humids areas. Were they live there is a dry seasson during december, january and february, the rest of the year its pretty rainy. The same happens with the B. baumgarteni, B. boehmei, B. smithi and A. bicoloratum.
I do not saying they can not live on dry substrate but on its real environment they live in humid and wet places.
Well, anyone is free to leave his tarantulas the way they want.
Please visit my picture thread to see the biotopes of the some brachys