As mcavana mentions, chew-out could be a problem in racks.

Mine have chewed off the plastic at the top of the aquariums too.

I built shelves above some snake racks, and keep 10 20-gallon aquariums in space I wasn't otherwise using.

Temperment varies. Mine are biters, but not the killing machines mcavana is raising. They seem to be getting mellower over time now that they're all used to my presence.