that cage can hold a max of 6 to 8 rats, depending on how big they are and such. it seems like a great cage, but has 1/2" bar spacing so if you have smaller rats you may need to cover the bars with mesh like hardware cloth. it seems like another version of the ferret nation, so it sounds pretty good.
I have one of these cages, not for my rats, but for my Sugar Gliders. The bar spacing is fine for rats, as glider are smaller than rats and they cannot escape(i can fit my finger in up to the first knuckle). The doors are large and make this cage great for cleaning and decorating. If i had the money i would have one for my ratty boys. But i say it is a great cage for ratties The wire is removeable, but the tray is plastic and may encourage chewing, i would say leave the wire and cover it with something (fleece or whatever)