I wish that my rats were as well-behaved as yours But I like these glass tubes; they seem like maybe they'll be easier to sanitize at cleaning time too. But I am keeping the plastic ones for one of my females, who has never chewed hers.. maybe it's a genetic thing, and some of the offspring of the chewers, chew too!
I know that it wasn't a case of it being dry; there was a lot of water in the cage after they chewed the most recent bottle victim.