the only problem with linersis that most cats will rip them appart when they are trying to cover the litter. They claw to get the litter to cover their business, and thier claws rip the flimsy plastic.
I had no choice when Vagabond had her kittens, I had to take the liners out, because she would claw and claw and claw when she would go to the bathroom. i didn't want any of the new kitties to get peices of plastic in them... bad for the digestive track lol

~ Salem