I'm in the same boat, for the months I've had mine, they have yet to exhibit this strong urge to chew like many claim they do.
Then again, lots of people have domestic rats chew out of racks all the time, I have never had that happen... I strongly believe it varies...
They prefer to chew the woods blocks and run all day... Like I said, we'll see how it goes! Any violaters will be terminated! hahaha