Even though drop-in pans are an absolute pain to clean, I would consider buying one for one of my FN's. One of my chins is driving me up the wall. He has only ONE corner he pees in, and he shoves all of the bedding away from this corner (thus spilling it outside the cage...ugh...) so he can pee on the metal. I replace the bedding and he does it the next time he has to pee. How much are these drop in grids and can you add them to the already existing pans I own? If you know, that is. Curious, because this bugger is driving me nuts.