I don't know your cutoff for "big breeders". We're running over 60 adult balls at the moment, and all thar are over about 1500 gms are in 41 qt tubs (Vision and ARS). As far as I've seen, the really big breeders are using the same size for their adults. I honestly think adult balls would actually tend to not do as well in much larger accomodations-these are secretive animals which in the wild spend most of their time packed tightli in burrows and hollows.