None of my rodent racks have even begun to warp. The one in the middle has been in service for almost 3 years.

Don't let us discourage you from going ahead with your plans. If you can afford to buy a rack, then by all means go for it, I only mentioned it because of the water issue. If I had water bottles instead of edstrom valves, I would have gone crazy by now. If you can work out the watering on the systems that you are looking at then great, and if not then you won't be the only one with bottles, I'm just not going to join you!