Does anyone use a Litter Maid? We are considering getting one. First of all, are they safe? Do they work? Would it be practical with 7 cats? One of the probalems I have heard concerning it is that it makes a lot of noise and scares the cats. I don`t want to invest that much money into something that the cats won`t use. I would appreciate any information, experiences, advice anyone can offer, both positive and negative. Thanks!